Electromagnetic clutch device

ABSTRACT

An electromagnetic clutch device includes: a meshing member; an electromagnetic coil; an armature; a cylindrical cam member; and a locking portion. The cam member is provided with a plurality of locked portions to be locked by the locking portion at different axial positions, such that the plurality of locked portions is formed adjacent to each other in a circumferential direction; the cam member rotates only by a first predetermined angle due to an axial movement of the armature from a first position to a second position, and the cam member further rotates only by a second predetermined angle due to a movement of the armature from the second position to the first position; and when locking of the locking portion is shifted from one of the plurality of locked portions to another locked portion circumferentially adjacent thereto so that the locking portion locks the another locked portion at a different axial position, the second meshing portion is meshed with the first meshing portion.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2013-189159,2013-189160 and 2013-189161 filed on Sep. 12, 2013 including thespecification, drawings and abstract is incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electromagnetic clutch deviceoperated by a magnetic force of an electromagnetic coil.

2. Description of Related Art

There has been described a clutch device configured to switch betweentransmission and cutoff of a torque by electromagnetic means (seeJapanese Patent Application Publication No. 2001-80385 (JP 2001-80385A), Japanese Patent Application Publication No. 2010-164175 (JP2010-164175 A), Japanese Patent Application Publication No. 2010-254058(JP 2010-254058 A)).

A driving force switch mechanism described in JP 2001-80385 A isprovided in a driving-force transmission path of a vehicle and functionsas a clutch device for switching between a two-wheel-drive state and afour-wheel-drive state. The driving force switch mechanism includes anactuator including an electric motor and a speed reducer, a rack forconverting a rotation of an output gear of the actuator into an axialdisplacement, and a sleeve spline-engaged with a first rotational memberand a second rotational member due to an axial movement of the rack.When the first rotational member is connected to the second rotationalmember in a torque transmittable manner, a current is supplied to anelectric motor so as to axially move the rack by the rotation of theoutput gear decelerated by the speed reducer, thereby causing the sleeveto be spline-engaged with the first rotational member and the secondrotational member. Hereby, the driving-force transmission path of adrive source of the vehicle is switched, so that a drive state of thevehicle is switched from the two-wheel-drive state to thefour-wheel-drive state.

Further, a tooth clutch described in JP 2010-164175 A includes a yokefor retaining an exciting coil, an armature drawn toward a yoke side bya magnetic force, and a pulley that rotate integrally with the armatureby a biasing force of a leaf spring, and is configured such that atorque is transmitted by meshing between mound-shaped toothing portionsformed on respective facing surfaces of the yoke and the armature.

A driving force transmission device described in JP 2010-254058 Aincludes: an actuator including an electric motor and a speed reducer; apinion gear rotationally driven by the actuator; a shift rod drivenaxially via a rack gear meshed with the pinion gear; and a couplingsleeve to be switched between a coupled state in which the couplingsleeve is meshed with a clutch gear by reciprocation by a shift forkmounted in the shift rod and an uncoupled state in which the couplingsleeve is uncoupled from the clutch gear. The coupling sleeve and theclutch gear constitute a meshing clutch mechanism. In a state where thecoupling sleeve is meshed with the clutch gear, a four-wheel-drive statewhere a driving force is transmitted to front and rear wheels isachieved. When the coupling sleeve is uncoupled from the clutch gear, atwo-wheel-drive state where a driving force is transmitted only to thefront wheels is achieved. Further, a spring for biasing the shift rodand the shift fork in a coupling direction where the coupling sleeve iscoupled to the clutch gear is disposed between the shift rod and a casemember.

At the time when the four-wheel drive state switches to thetwo-wheel-drive state, a pinion gear is rotationally driven by anelectric motor, so that the coupling sleeve is meshed with the clutchgear against a biasing force of the spring. Further, at the time whenthe two-wheel drive state switches to the four-wheel-drive state, theshift fork is changed into a free state, so that the coupling sleeve ispressed against an end surface of the clutch gear by the biasing forceof the spring, and when a rotation of the coupling sleeve issynchronized with a rotation of the clutch gear, the coupling sleeve ismeshed with the clutch gear by the biasing force of the spring.

SUMMARY OF THE INVENTION

In the meantime, in a case where wheel assemblies skid while a vehicleis running on a low μ road such as a wet road surface in thetwo-wheel-drive state, it is necessary to switch the two-wheel-drivestate to the four-wheel-drive state quickly so as to stabilize therunning of the vehicle. However, the technique described in JP2001-80385 A may cause such a problem that a rotation of a rotor of theelectric motor is decelerated and is output from the output gear, and arotation of the output gear is converted into an axial displacement bythe rack so that the sleeve axially moves, which may result in that theswitching to the four-wheel drive state is not necessarily performedquickly. In view of this, such an electromagnetic clutch device has beendemanded that is able to quickly switch between a coupled state in whichthe first rotational member is coupled to the second rotational memberand an uncoupled state in which the first rotational member and thesecond rotational member are rotatable relative to each other.

Note that, in the tooth clutch described in JP 2010-164175 A, when thetoothing portions are directly meshed with each other by an axialmovement of the armature, it is possible to quickly switch between thecoupled state and the uncoupled state. However, in the clutch configuredas such, it is difficult to transmit a large torque such as a drivingforce of the vehicle, for example.

Further, in a case where wheel assemblies skid while a vehicle isrunning on a low μ road such as a wet road surface in thetwo-wheel-drive state, it is necessary to switch the two-wheel-drivestate to the four-wheel-drive state quickly so as to stabilize therunning of the vehicle. However, in the technique described in JP2010-254058 A, the switching to the four-wheel-drive state is notperformed until rotations of the coupling sleeve and the clutch gear aresynchronized with each other, which may result in that the switching tothe four-wheel drive state is not necessarily performed quickly. Even ina case where a pair of rotational members rotates relative to eachother, such an electromagnetic clutch device has been demanded that isable to couple the pair of rotational members to each other immediately.

In view of this, the present invention provides an electromagneticclutch device that is able to achieve a large torque transmissioncapacity and to improve responsiveness of switching between a coupledstate and an uncoupled state of a first rotational member and a secondrotational member that are rotatable relative to each other

Further, the present invention provides an electromagnetic clutch devicethat is able to improve responsiveness of switching from an uncoupledstate to a coupled state of a first rotational member and a secondrotational member that are rotatable relative to each other.

An electromagnetic clutch device according to a first aspect of thepresent invention is an electromagnetic clutch device configured toconnect a first rotational member to a second rotational member in atorque transmittable manner, and includes: a meshing member including asecond meshing portion to be meshed with a first meshing portion formedin the first rotational member, the meshing member being connected tothe second rotational member in an axially movable but relativelynon-rotatable manner; an electromagnetic coil that cause a magneticforce by current application; an armature that axially move due to themagnetic force; a cylindrical cam member that axially move the meshingmember so that the second meshing portion is meshed with the firstmeshing portion; and a locking portion provided so as to be axiallyimmovable relative to the first rotational member and to benon-rotatable relative to the armature. The cam member is provided witha plurality of locked portions to be locked by the locking portion atdifferent axial positions, such that the plurality of locked portions isformed adjacent to each other in a circumferential direction; the cammember rotates only by a first predetermined angle due to an axialmovement of the armature from a first position to a second position, andthe cam member further rotates only by a second predetermined angle dueto a movement of the armature from the second position to the firstposition; and when locking of the locking portion is shifted from one ofthe plurality of locked portions to another locked portioncircumferentially adjacent thereto so that the locking portion locks theanother locked portion at a different axial position, the second meshingportion is meshed with the first meshing portion.

According to the above aspect, it is possible to improve responsivenessof switching between a coupled state and an uncoupled state of the firstrotational member and the second rotational member that are rotatablerelative to each other.

An electromagnetic clutch device according to a second aspect of thepresent invention is an electromagnetic clutch device configured toconnect a first rotational member to a second rotational member in atorque transmittable manner, and includes: a meshing member including asecond meshing portion to be meshed with a first meshing portionprovided in the second rotational member, the meshing member beingconnected to the first rotational member in an axially movable butrelatively non-rotatable manner; an electromagnetic coil that cause amagnetic force by current application; an armature that axially move dueto the magnetic force; a biasing member that bias the meshing member ina direction where the second meshing portion is meshed with the firstmeshing portion; and a pressing mechanism including a locking portionthat press the meshing member against a biasing force of the biasingmember due to an axial movement of the armature so as to axially movethe meshing member, the locking portion being provided so as to beaxially immovable and relatively non-rotatable relative to a housingthat support the electromagnetic coil, and a cylindrical cam memberprovided with a plurality of locked portions to be locked by the lockingportion at different axial positions, the pressing mechanism beingconfigured such that, in response to an axial movement of the armature,locking of the locking portion is shifted from one of the plurality oflocked portions to another locked portion placed at a different axialposition. When the cam member moves to an opposite side to the meshingmember in response to the axial movement of the armature, the secondmeshing portion is meshed with the first meshing portion due to thebiasing force of the biasing member.

According to the above aspect, it is possible to improve responsivenessof switching from an uncoupled state to a coupled state of the firstrotational member and the second rotational member that are rotatablerelative to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a sectional view of an electromagnetic clutch device accordingto a first embodiment of the present invention;

FIG. 2 is a perspective view illustrating an armature;

FIG. 3 is a perspective view illustrating a plurality of lockingportions provided in a second housing member;

FIG. 4A is a plane view of a cam member;

FIG. 4B is a perspective view illustrating part of the cam member;

FIG. 5A is a schematic view to describe an operation at the time whenthe cam member rotates and axially moves due to an axial movement of thearmature;

FIG. 5B is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature;

FIG. 5C is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature;

FIG. 5D is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature;

FIG. 5E is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature;

FIG. 6A is a schematic view illustrating an uncoupled state between aplurality of gear teeth of a first rotational member and a plurality ofgear teeth of a meshing member;

FIG. 6B is a schematic view illustrating a coupled state between theplurality of gear teeth of the first rotational member and the pluralityof gear teeth of the meshing member;

FIG. 6C is a partially enlarged view of a part B in FIG. 6B;

FIG. 7 is a sectional view of an electromagnetic clutch device accordingto a second embodiment;

FIG. 8 is a perspective view illustrating a cam member according to thesecond embodiment;

FIG. 9A is an operation explanatory view illustrating the cam memberaccording to the second embodiment and an armature as well as a lockingportion;

FIG. 9B is an operation explanatory view illustrating the cam memberaccording to the second embodiment and the armature as well as thelocking portion;

FIG. 9C is an operation explanatory view illustrating the cam memberaccording to the second embodiment and the armature as well as thelocking portion;

FIG. 9D is an operation explanatory view illustrating the cam memberaccording to the second embodiment and the armature as well as thelocking portion;

FIG. 10A is a schematic view to describe an operation at the time whenthe cam member rotates and axially moves in an axial direction due to anaxial movement of the armature according to the second embodiment;

FIG. 10B is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature according to the second embodiment;

FIG. 10C is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature according to the second embodiment;

FIG. 10D is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature according to the second embodiment;

FIG. 10E is a schematic view to describe the operation at the time whenthe cam member rotates and axially moves due to the axial movement ofthe armature according to the second embodiment;

FIG. 11 is a sectional view of an electromagnetic clutch deviceaccording to a third embodiment;

FIG. 12 is a perspective view illustrating an armature according to thethird embodiment;

FIG. 13 is a perspective view illustrating a plurality of lockingportions provided in a second housing member according to the thirdembodiment;

FIG. 14 is a perspective view illustrating a cam member according to thethird embodiment;

FIG. 15A is a perspective view of a pressing mechanism and illustratesthe cam member according to the third embodiment as well as pressingprojections of the armature and the locking portions;

FIG. 15B is a perspective view of the pressing mechanism and illustratesthe cam member according to the third embodiment as well as the pressingprojections of the armature and the locking portions;

FIG. 15C is a perspective view of the pressing mechanism and illustratesthe cam member according to the third embodiment as well as the pressingprojections of the armature and the locking portions;

FIG. 15D is a perspective view of the pressing mechanism and illustratesthe cam member according to the third embodiment as well as the pressingprojections of the armature and the locking portions;

FIG. 16A is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe an operation of thepressing mechanism according to the third embodiment;

FIG. 16B is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe the operation ofthe pressing mechanism according to the third embodiment;

FIG. 16C is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe the operation ofthe pressing mechanism according to the third embodiment;

FIG. 16D is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe the operation ofthe pressing mechanism according to the third embodiment;

FIG. 17A is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe an operation of thepressing mechanism at the time when the electromagnetic clutch deviceaccording to the third embodiment is shifted from an uncoupled state toa coupled state;

FIG. 17B is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe the operation ofthe pressing mechanism at the time when the electromagnetic clutchdevice according to the third embodiment is shifted from the uncoupledstate to the coupled state;

FIG. 17C is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe the operation ofthe pressing mechanism at the time when the electromagnetic clutchdevice according to the third embodiment is shifted from the uncoupledstate to the coupled state;

FIG. 17D is a schematic view of the cam member, the pressing projectionof the armature, and the locking portion to describe the operation ofthe pressing mechanism at the time when the electromagnetic clutchdevice according to the third embodiment is shifted from the uncoupledstate to the coupled state;

FIG. 18 is an enlarged view illustrating an electromagnetic clutchdevice according to a fourth embodiment;

FIG. 19 is an enlarged view illustrating the electromagnetic clutchdevice according to the fourth embodiment;

FIG. 20 is a sectional view of the electromagnetic clutch deviceaccording to the fourth embodiment and its vicinal area;

FIG. 21A is a plane view and a sectional view of a first rotationalmember according to the fourth embodiment;

FIG. 21B is a plane view and a sectional view of the first rotationalmember according to the fourth embodiment;

FIG. 21C is a plane view and a sectional view of the first rotationalmember according to the fourth embodiment;

FIG. 22A is a plane view of a friction member according to the fourthembodiment;

FIG. 22B is a plane view of the friction member according to the fourthembodiment;

FIG. 22C is an enlarged perspective view of an outer peripheral portionof the friction member according to the fourth embodiment;

FIG. 23A is a plane view of a key;

FIG. 23B is a side view of the key;

FIG. 23C is a perspective view of the key;

FIG. 24A is an operation explanatory view to describe an operation ofthe electromagnetic clutch device;

FIG. 24B is an operation explanatory view to describe the operation ofthe electromagnetic clutch device; and

FIG. 24C is an operation explanatory view to describe the operation ofthe electromagnetic clutch device.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a sectional view of an electromagnetic clutch device accordingto a first embodiment of the present invention and its vicinal area. Theelectromagnetic clutch device is used to intermittently transmit adriving force of a driving source such as an engine of a vehicle, forexample.

An electromagnetic clutch device 1 connects a first rotational member 11to a second rotational member 12 in a torque transmittable manner. Thefirst rotational member 11 and the second rotational member 12 have acommon rotation axis O so as to be coaxially supported by a housing 10in a relatively rotatable manner. The housing 10 is constituted by afirst housing member 101 and a second housing member 102, and the firsthousing member 101 and the second housing member 102 are fixed to eachother via a plurality of bolts 100 (only one bolt 100 is illustrated inFIG. 1).

The first rotational member 11 is rotatably supported by a ball bearing16 placed between the first rotational member 11 and the first housingmember 101. The first rotational member 11 integrally includes a shaftportion 117 supported by the ball bearing 16, an overhanging portion 116formed to overhang radially outwardly from an end of the shaft portion117, a cylindrical portion 113 extending from an outer end of theoverhanging portion 116 toward the second rotational member 12 along therotation axis O, and a gear flange portion 114 formed to overhangfurther radially outwardly from a tip end of the cylindrical portion 113and serving as a first meshing portion. A plurality of gear teeth 115 isformed in the gear flange portion 114 along a circumferential directionthereof.

The second rotational member 12 is formed in a cylindrical shape havingan insertion hole 120 formed so that a shaft 13 inserted from an opening102 a formed in the second housing member 102 passes therethrough, andan inner peripheral spline portion 12 a splined to an outer peripheralspline portion 13 a of the shaft 13 is formed on an inner surface of theinsertion hole 120. The second rotational member 12 and the shaft 13 arenot rotatable relative to each other due to the splining between theinner peripheral spline portion 12 a and the outer peripheral splineportion 13 a, and an axial relative movement thereof is regulated by asnap ring 14. A sealing member 15 is provided so as to seal between anouter peripheral surface of the shaft 13 and an inner surface of theopening 102 a of the second housing member 102.

One axial end of the second rotational member 12 is supported by a ballbearing 17 placed on an inner side of the cylindrical portion 113 of thefirst rotational member 11, and the other axial end thereof is supportedby a ball bearing 18 placed between the second rotational member 12 andthe second housing member 102. The ball bearings 17, 18 are fitted to anouter peripheral surface of the second rotational member 12, and anouter peripheral spline portion 12 b is formed on the outer peripheralsurface of the second rotational member 12 between the ball bearing 17and the ball bearing 18 so as to be parallel to the rotation axis O. Theelectromagnetic clutch device 1 is placed between the outer peripheralsurface of the second rotational member 12 and the housing 10.

The electromagnetic clutch device 1 includes: a meshing member 2connected to the second rotational member 12 so as to be axially movablebut relatively non-rotatable relative to the second rotational member12; an electromagnetic coil 3 for generating a magnetic force by currentapplication; an armature 4 to be axially moved by the magnetic force ofthe electromagnetic coil 3; a cylindrical cam member 5 outwardly engagedto the second rotational member 12; a plurality of locking portions 19provided so as to be axially immovable relative to the first rotationalmember 11 and non-rotatable relative to the armature 4; a rollingbearing 6 placed between the meshing member 2 and the cam member 5; anelastic member 7 that elastically press the meshing member 2 toward thecam member 5; and a coned disc spring 301 as a biasing member that biasthe armature 4 toward an opposite side to the electromagnetic coil 3.

The cam member 5 is placed between the rolling bearing 6, and thearmature 4 and the plurality of locking portions 19 so as to receive apressing force of the elastic member 7 as an axial biasing force towardthe plurality of locking portions 19 from the meshing member 2 via therolling bearing 6. The locking portions 19 are formed as projectionsprojecting closer to the cam member 5 than that facing surface of thesecond housing member 102 which is axially opposed to the armature 4. Inthe present embodiment, the plurality of locking portions 19 is formedintegrally with the second housing member 102, but the plurality oflocking portions 19 may be formed separately from the second housingmember 102.

Further, in the present embodiment, the rolling bearing 6 is constitutedby a needle thrust roller bearing. The elastic member 7 is configured byplacing a pair of coned disc springs 71, 72 to face each other, and isplaced on a first-rotational-member-11 side of the meshing member 2. Theconed disc spring 71 makes contact with an axial end surface of themeshing member 2, and the coned disc spring 72 makes contact with anaxial end surface of an inner ring 171 of the ball bearing 17constituted by the inner ring 171, an outer ring 172, and a plurality ofspherical rolling elements 173.

The meshing member 2 integrally includes: a cylindrical portion 21having an inner peripheral spline portion 21 a splined to the outerperipheral spline portion 12 b of the second rotational member 12; and agear flange portion 22 formed to overhang radially outwardly from afirst-rotational-member-11-side end of the cylindrical portion 21 andserving as a second meshing portion. The meshing member 2 is connectedto the second rotational member 12 so as to be axially movable butrelatively non-rotatable relative to the second rotational member 12,and when the meshing member 2 moves toward the first rotational member11, the gear flange portion 22 is meshed with the gear flange portion114 of the first rotational member 11.

A plurality of gear teeth 23 is formed in the gear flange portion 22along a circumferential direction thereof, and the plurality of gearteeth 23 is meshed with the plurality of gear teeth 115 of the gearflange portion 114. An upper side relative to the rotation axis O inFIG. 1 illustrates a state (uncoupled state) where the gear flangeportion 22 of the meshing member 2 is not meshed with the gear flangeportion 114 of the first rotational member 11. A lower side relative tothe rotation axis O in FIG. 1 illustrates a state (coupled state) wherethe gear flange portion 22 of the meshing member 2 is meshed with thegear flange portion 114 of the first rotational member 11.

In response to an axial movement of the armature 4, the cam member 5presses the meshing member 2 axially along the rotation axis O so thatthe gear flange portion 22 of the meshing member 2 is meshed with thegear flange portion 114 of the first rotational member 11. Details of apressing mechanism in which the cam member 5 presses the meshing member2 will be described later.

The electromagnetic coil 3 is formed by winding, around a bobbin 31 madefrom resin, a winding 32 through which a current supplied from acontroller (not shown) flows. The electromagnetic coil 3 is held by anannular yoke 30 made from a ferromagnetic material such as iron, and theyoke 30 is supported by the second housing member 102. The yoke 30 has aplurality of holes 30 a to which columnar pins 300 placed in parallelwith the rotation axis O are fitted, and one ends of the pins 300 areinserted into the holes 30 a. Further, the second housing member 102 hasa plurality of holes 102 b to which the other ends of the pins 300 arefitted.

FIG. 2 is a perspective view illustrating the armature 4. The armature 4integrally includes: an annular-disk shaped main body 40 having, in itscenter, a through hole 4 a through which the second rotational member 12passes; and a plurality of (six in the present embodiment) pressingprojections 41 projecting from an inner peripheral surface of thethrough hole 4 a toward the center of the main body 40. In the main body40, pin insertion holes 4 b through which a plurality of pins 300(illustrated in FIG. 1) passes are formed at several places (four placesin the present embodiment) around the through hole 4 a. That facingsurface 41 a of the pressing projection 41 which is opposed to axial endsurfaces 51 a, 52 a of first and second locked portions 51, 52 of thecam member 5 (described later) is formed as an inclined surface that isinclined with respect to a thickness direction (a direction parallel tothe rotation axis O) of the main body 40.

As illustrated in FIG. 1, the armature 4 is elastically pressed, in adirection to be distanced from the yoke 30, by the coned disc spring 301placed between the main body 40 and the yoke 30. When no current isapplied to the electromagnetic coil 3, the armature 4 abuts with areceiving portion 102 c of the second housing member 102 due to apressing force of the coned disc spring 301, and when a current isapplied to the electromagnetic coil 3, the armature 4 is drawn to theyoke 30 by a magnetic force thereof.

Further, a rotation of the armature 4 relative to the second housingmember 102 and the yoke 30 is regulated by the plurality of pins 300passing through the pin insertion holes 4 b, so that the armature 4 isaxially movable but relatively non-rotatable relative to theelectromagnetic coil 3. The armature 4 is guided by the plurality ofpins 300 so as to axially move between a first position in which thearmature 4 abuts with the receiving portion 102 c of the second housingmember 102 and a second position in which the armature 4 abuts with theyoke 30. The coned disc spring 301 biases the armature 4 from the secondposition toward the first position. The upper side relative to therotation axis O in FIG. 1 illustrates a state where the armature 4 isplaced in the first position, and the lower side relative to therotation axis O in FIG. 1 illustrates a state where the armature 4 isplaced in the second position.

FIG. 3 is a perspective view illustrating the plurality of lockingportions 19 provided in the second housing member 102 and its vicinalarea.

The second housing member 102 has a through hole 102 d through which thesecond rotational member 12 passes, and the plurality of lockingportions 19 projects from an inner peripheral surface of the throughhole 102 d toward the second rotational member 12, and also projectstoward the cam member 5 along the rotation axis O. The plurality oflocking portions 19 is provided at regular intervals along acircumferential direction of the through hole 102 d, and the number ofthe locking portions 19 is the same as the number of the pressingprojections 41 of the armature 4. Similarly to the facing surface 41 aof the pressing projection 41 of the armature 4, the locking portion 19is formed such that that tip end surface 19 a of the locking portion 19which is opposed to the axial end surfaces 51 a, 52 a of the first andsecond locked portions 51, 52 of the cam member 5 (described later) isformed as an inclined surface that is inclined with respect to thedirection parallel to the rotation axis O.

FIG. 4A is a plane view of the cam member 5 viewed from a side of theplurality of locking portions 19 along the rotation axis O, and FIG. 4Bis a perspective view illustrating part of the cam member 5.

In the cam member 5, a plurality of locked portions locked by thelocking portion 19 at different axial positions are formed so as to beadjacent to each other in a circumferential direction. In the presentembodiment, the plurality of locked portions is constituted by a firstlocked portion 51 and a second locked portion 52, and the first lockedportion 51 and the second locked portion 52 are formed alternately inthe circumferential direction. That base end surface 5 a of the cammember 5 which makes contact with the rolling bearing 6 is formed as aflat surface perpendicular to the direction parallel to the rotationaxis O. The first locked portion 51 is formed in a position closer tothe base end surface 5 a than the second locked portion 52.

As illustrated in FIG. 4A, twelve first locked portions 51 and twelvesecond locked portions 52 are formed alternately in the cam member 5 inthe circumferential direction. When the cam member 5 is viewed from adirection shown in FIG. 4A, a wall portion 53 axially projecting isformed between the second locked portion 52 and the first locked portion51 adjacent to the second locked portion 52 in a clockwise direction.The wall portion 53 functions as a partition wall that sections thefirst locked portion 51 and the second locked portion 52. One endsurface out of both end surfaces of the wall portion 53 in thecircumferential direction faces the first locked portion 51 as a firstwall surface 53 b, and the other end surface faces the second lockedportion 52 as a second wall surface 53 c. An end surface 53 a of thewall portion 53 in an axial direction of the cam member 5 is inclined sothat a first-wall-surface-53 b side thereof is placed closer to the baseend surface 5 a than a second-wall-surface-53 c side thereof.

The axial end surface 51 a in an axial end of the first locked portion51 and the axial end surface 52 a in an axial end of the second lockedportion 52 are formed so as to be inclined with respect to thecircumferential direction of the cam member 5. More specifically, theaxial end surface 51 a of the first locked portion 51 is a flat surfaceinclined so that a second-locked-portion-52 side thereof is placedcloser to the base end surface 5 a than a wall-portion-53 side thereof,and the axial end surface 52 a of the second locked portion 52 is a flatsurface inclined so that a wall-portion-53 side thereof is placed closerto the base end surface 5 a than a first-locked-portion-51 side thereof.

A wall surface 50 a in the circumferential direction is formed betweenthat end of the axial end surface 51 a of the first locked portion 51which is opposite to the wall portion 53, and that end of the axial endsurface 52 a of the second locked portion 52 which is opposite to thewall portion 53. The wall surface 50 a is formed as a flat surfaceparallel to the rotation axis O as a stepped surface between the firstlocked portion 51 and the second locked portion 52. An angle formedbetween the axial end surface 51 a of the first locked portion 51 andthe wall surface 50 a is an acute angle.

Further, the axial end surface 52 a of the second locked portion 52 isinclined with respect to the circumferential direction of the cam member5 at the same angle as that of the axial end surface 51 a of the firstlocked portion 51, and an angle formed between the axial end surface 52a and the second wall surface 53 c of the wall portion 53 is an acuteangle.

The facing surface 41 a of the pressing projection 41 of the armature 4and the tip end surface 19 a of the locking portion 19 abut with theaxial end surface 51 a of the first locked portion 51 and the axial endsurface 52 a of the second locked portion 52. The facing surface 41 a ofthe armature 4 abuts with outer parts of the axial end surfaces 51 a, 52a in a radial direction of the cam member 5, and the tip end surface 19a of the locking portion 19 abuts with inner parts of the axial endsurfaces 51 a, 52 a in the radial direction of the cam member 5. The cammember 5 receives, due to the elastic member 7, an axial biasing forceat which the axial end surfaces 51 a, 52 a are pressed against thepressing projection 41 of the armature 4 and the locking portion 19.

FIGS. 5A to 5E are schematic views to describe an operation at the timewhen the cam member 5 rotates and moves axially due to an axial movementof the armature 4. The electromagnetic clutch device 1 is configuredsuch that: the cam member 5 rotates only by a first predetermined angledue to a movement of the armature 4 from the first position to thesecond position; the cam member 5 further rotates only by a secondpredetermined angle due to a movement of the armature 4 from the secondposition to the first position; and locking of the locking portion 19 isshifted from one of the plurality of locked portions to another lockedportion circumferentially adjacent thereto so that the locking portion19 locks the another locked portion at a different axial position, andhereby, the plurality of gear teeth 23 of the gear flange portion 22 ismeshed with the plurality of gear teeth 115 of the gear flange portion114. The following describes the electromagnetic clutch device 1 morespecifically with reference to FIGS. 5A to 5E.

FIG. 5A illustrates a first state where the locking portion 19 locks thefirst locked portion 51, and the armature 4 is placed in the firstposition. In the first state, the axial end surface 51 a of the firstlocked portion 51 is pressed against the tip end surface 19 a of thelocking portion 19 by a biasing force of the elastic member 7, and isalso opposed to the facing surface 41 a of the pressing projection 41 ofthe armature 4. Further, the locking portion 19 abuts with the wallsurface 50 a, and the pressing projection 41 of the armature 4 isopposed to the axial end surface 51 a in a position distanced from thewall surface 50 a in the circumferential direction of the cam member 5.

FIG. 5B illustrates a second state where a current is applied to theelectromagnetic coil 3, and the armature 4 moves to the second positionfrom the first state illustrated in FIG. 5A. The facing surface 41 a ofthe pressing projection 41 of the armature 4 abuts with the axial endsurface 51 a in a course of shifting from the first state to the secondstate, and the pressing projection 41 presses and moves the cam member 5toward the meshing member 2. Further, in the second state, due to themovement of the cam member 5, a state where the locking portion 19 abutswith the wall surface 50 a is released.

FIG. 5C illustrates a third state where, due to sliding between theaxial end surface 51 a of the first locked portion 51 and the facingsurface 41 a of the pressing projection 41 of the armature 4, the cammember 5 rotates in an arrow-A direction only by the first predeterminedangle. Due to the rotation of the cam member 5, the wall surface 50 aabuts with a side surface 41 b (a circumferential end surface of thepressing projection 41) of the pressing projection 41 of the armature 4.

That is, when the armature 4 moves from the first position to the secondposition in the axial direction, the armature 4 presses the cam member 5toward the meshing member 2 and rotates the cam member 5 only by thefirst predetermined angle. The first predetermined angle is an anglecorresponding to a distance d1 of a gap between the side surface 41 b ofthe pressing projection 41 of the armature 4 and the wall surface 50 a,as illustrated in FIGS. 5A and 5B.

When the armature 4 is placed in the second position, the tip endsurface 19 a of the locking portion 19 is opposed to the axial endsurface 52 a of the second locked portion 52 via a gap. That is, whenthe armature 4 moves to the second position, the cam member 5 rotates bythe first predetermined angle and the pressing projection 41 abuts withthe wall surface 50 a, and the tip end surface 19 a of the lockingportion 19 is opposed to the axial end surface 52 a of the second lockedportion 52 adjacent to the first locked portion 51.

FIG. 5D illustrates a fourth state where current application to theelectromagnetic coil 3 is stopped, and the armature 4 is in the middleof returning to the first position from the second position. In thefourth state, the tip end surface 19 a of the locking portion 19 abutswith the axial end surface 52 a of the second locked portion 52. Whenthe tip end surface 19 a of the locking portion 19 abuts with the axialend surface 52 a of the second locked portion 52, a rotational forcetoward the arrow-A direction is applied to the cam member 5, but therotation of the cam member 5 to the arrow-A direction is regulated byabutment of the side surface 41 b of the pressing projection 41 of thearmature 4 with respect to the wall surface 50 a.

FIG. 5E illustrates a fifth state where the armature 4 returns to thefirst position, the cam member 5 rotates in the arrow-A direction untilthe second wall surface 53 c of the wall portion 53 abuts with a sidesurface 19 b of the locking portion 19. In the fifth state, due tosliding between the tip end surface 19 a of the locking portion 19 andthe axial end surface 52 a of the second locked portion 52 of the cammember 5 that receives the biasing force of the elastic member 7, thecam member 5 rotates relative to the locking portion 19 by the secondpredetermined angle. Hereby, the locking portion 19 locks the secondlocked portion 52. The second predetermined angle is an anglecorresponding to a distance d2 between the second wall surface 53 c ofthe wall portion 53 and the locking portion 19 in the third stateillustrated in FIG. 5D.

That is, when the armature 4 moves from the second position to the firstposition, the cam member 5 further rotates only by the secondpredetermined angle, and hereby, the locking portion 19 locks the secondlocked portion 52 adjacent to the first locked portion 51. As describedabove, the first locked portion 51 and the second locked portion 52 areplaced in different positions in the axial direction of the cam member5, and a distance d3 (illustrated in FIG. 5A) from the base end surface5 a to the axial end surface 52 a of the second locked portion 52 islonger than a distance d4 (illustrated in FIG. 5A) from the base endsurface 5 a to the axial end surface 51 a of the first locked portion51. Thus, the cam member 5 axially moves due to the shifting from thefirst state illustrated in FIG. 5A to the fifth state illustrated inFIG. 5E, and the meshing member 2 is moved so that the gear flangeportion 22 is meshed with the gear flange portion 114 of the firstrotational member 11. Hereby, the gear flange portion 22 of the meshingmember 2 is meshed with the gear flange portion 114 of the firstrotational member 11, thereby achieving a coupled state where a torqueis transmittable between the first rotational member 11 and the secondrotational member 12.

When the armature 4 moves from the first position to the second positionand then further returns to the first position after the firstrotational member 11 and the second rotational member 12 enter thecoupled state, the locking portion 19 locks the first locked portion 51,so that the meshing between the gear flange portion 114 of the firstrotational member 11 and the gear flange portion 22 of the meshingmember 2 is released, thereby causing the first rotational member 11 andthe second rotational member 12 to enter an uncoupled state.

An operation of the armature 4 and the cam member 5 at the time ofshifting from the coupled state to the uncoupled state is similar to theoperation described with reference to FIG. 5. That is, from the stateillustrated in FIG. 5E, the armature 4 axially moves to press the cammember 5 toward the meshing member 2, so that the axial end surface 52 aof the second locked portion 52 slides over the facing surface 41 a ofthe pressing projection 41 until the side surface 41 b of the pressingprojection 41 abuts with the second wall surface 53 c of the wallportion 53, and thus, the cam member 5 rotates only by the firstpredetermined angle. At this time, the tip end surface 19 a of thelocking portion 19 is opposed to the end surface 53 a of the wallportion 53.

When the armature 4 returns to the first position, the end surface 53 aof the wall portion 53 and the axial end surface 51 a of the firstlocked portion 51 slide over the tip end surface 19 a of the lockingportion 19, so that the cam member 5 rotates only by the secondpredetermined angle, and the locking portion 19 locks the first lockedportion 51. The second predetermined angle in this case is an anglecorresponding to a distance between the wall surface 50 a and thelocking portion 19 in a state where the side surface 41 b of thepressing projection 41 abuts with the second wall surface 53 c of thewall portion 53.

As such, when the armature 4 reciprocates between the first position andthe second position, a state where the locking portion 19 locks thefirst locked portion 51 and a state where the locking portion 19 locksthe second locked portion 52 are switched. When the locking portion 19locks the second locked portion 52, the plurality of gear teeth 23 ofthe gear flange portion 22 is meshed with the plurality of gear teeth115 of the gear flange portion 114. When the locking portion 19 locksthe first locked portion 51, the meshing between the plurality of gearteeth 23 of the gear flange portion 22 and the plurality of gear teeth115 of the gear flange portion 114 is released.

FIGS. 6A to 6C schematically illustrate the plurality of gear teeth 115of the gear flange portion 114 of the first rotational member 11 and theplurality of gear teeth 23 of the gear flange portion 22 of the meshingmember 2. FIG. 6A is a schematic view illustrating the uncoupled state,FIG. 6B is a schematic view illustrating the coupled state, and FIG. 6Cis an enlarged view of a part B in FIG. 6B.

In the uncoupled state illustrated in FIG. 6A, the plurality of gearteeth 115 of the first rotational member 11 is not meshed with theplurality of gear teeth 23 of the meshing member 2, so that the firstrotational member 11 and the second rotational member 12 are rotatablerelative to each other.

When the meshing member 2 is pressed by the cam member 5 and movestoward the first rotational member 11, the plurality of gear teeth 23 ofthe meshing member 2 comes inside between the plurality of gear teeth115 of the first rotational member 11 as illustrated in FIG. 6B, so thatthe gear teeth 115 are meshed with the gear teeth 23 so that they are inthe coupled state.

In the coupled state, when a torque is transmitted from the firstrotational member 11 to the second rotational member 12, tooth flanks 23a of the gear teeth 23 of the meshing member 2 receive a pressure P fromtooth flanks 115 a of the gear teeth 115 of the first rotational member11 due to the torque, as illustrated in FIG. 6C. Due to the pressure P,a circumferential component force P1 and an axial component force P2 areapplied to the meshing member 2.

The circumferential component force P1 becomes a torque to betransmitted to the second rotational member 12 via the meshing member 2,and the axial component force P2 is transmitted to the cam member 5 viathe rolling bearing 6. Hereby, the cam member 5 is pressed toward thelocking portion 19. However, the axial end surface 52 a of the secondlocked portion 52 of the cam member 5 abuts with the tip end surface 19a of the locking portion 19, so that an axial movement of the cam member5 is regulated. That is, the locking portion 19 receives the axialcomponent force P2 via the meshing member 2, the rolling bearing 6, andthe cam member 5, thereby regulating the axial movement of the cammember 5.

According to the first embodiment described above, it is possible toobtain the following operation/working-effect.

The meshing member 2 moves axially along with the axial movement of thearmature 4 from the first position to the second position so as to bemeshed with the first rotational member 11. Accordingly, in comparisonwith a case where an electric motor and a speed reducer are used as anactuator for operating a clutch device, it is possible to performswitching between the coupled state and the uncoupled state immediately.That is, responsiveness of switching improves.

The axial component force P2 that the meshing member 2 receives due totorque transmission between the first rotational member 11 and thesecond rotational member 12 is received by the locking portion 19 viathe cam member 5. This attains a large torque transmission capacity,thereby making it possible to transmit a large torque such as a drivingforce of the vehicle, for example.

The cam member 5 is configured such that the axial end surface 51 a ofthe first locked portion 51 and the axial end surface 52 a of the secondlocked portion 52 are inclined with respect to the circumferentialdirection, so that the axial end surfaces 51 a, 52 a slide over thefacing surface 41 a of the pressing projection 41 due to the axialmovement of the armature 4 from the first position to the secondposition, and thus, the cam member 5 rotates only by the firstpredetermined angle. Further, the cam member 5 is configured such thatthe axial end surface 51 a of the first locked portion 51, the axial endsurface 52 a of the second locked portion 52, and the end surface 53 aof the wall portion 53 are inclined with respect to the circumferentialdirection, so that the axial end surface 51 a of the first lockedportion 51, the axial end surface 52 a of the second locked portion 52,and the end surface 53 a of the wall portion 53 slide over the tip endsurface 19 a of the locking portion 19 due to the axial movement of thearmature 4 from the second position to the first position, and thus, thecam member 5 rotates only by the second predetermined angle. That is,since the cam member 5 rotates due to the axial movement of the armature4, it is possible to perform switching between a state where the lockingportion 19 locks the first locked portion 51 and a state where thelocking portion 19 locks the second locked portion 52, without arotational drive mechanism such as a motor for rotating the cam member5. This makes it possible to downsize the electromagnetic clutch device1 and to reduce cost thereof.

The elastic member 7 is placed on the first-rotational-member-11 side ofthe meshing member 2, and a biasing force thereof acts so as to distancethe meshing member 2 from the first rotational member 11 and to press,via the rolling bearing 6, the cam member 5 toward the locking portion19 and the pressing projection 41 of the armature 4. Hereby, the meshingbetween the gear flange portion 114 of the first rotational member 11and the gear flange portion 22 of the meshing member 2 is releasedimmediately at the time when the locking portion 19 locks the firstlocked portion 51. Further, sliding of the axial end surface 51 a of thefirst locked portion 51, the axial end surface 52 a of the second lockedportion 52, and the end surface 53 a of the wall portion 53 with respectto the facing surface 41 a of the pressing projection 41 and the tip endsurface 19 a of the locking portion 19 allows the cam member 5 torotate.

In a state where the locking portion 19 locks the second locked portion52 of the cam member 5 and current application to the electromagneticcoil 3 is stopped, the meshing member 2 is meshed with the firstrotational member 11. Accordingly, it is not necessary to continue thecurrent application to the electromagnetic coil 3 in the coupled state.This makes it possible to reduce power consumption and heat generationat the time of the operation of the electromagnetic clutch device 1.

Next will be described a second embodiment of the present invention withreference to FIGS. 7 to 10.

FIG. 7 is a sectional view of an electromagnetic clutch device 1Aaccording to the present embodiment. In FIG. 7, a constituent havingsubstantially the same function as a constituent of the electromagneticclutch device 1 described in the first embodiment has the same referencesign as in the electromagnetic clutch device 1, and a redundantdescription thereof is omitted.

Configurations of a first rotational member 11A, a meshing member 2A,and a cam member 5 of the electromagnetic clutch device 1A according tothe present embodiment are different from the configurations of thefirst rotational member 11, the meshing member 2, and the cam member 5of the electromagnetic clutch device 1 according to the firstembodiment.

The first rotational member 11A integrally includes a shaft portion 117,an overhanging portion 116, a cylindrical portion 113 extending from anouter end of the overhanging portion 116 toward a second rotationalmember 12 along a rotation axis O, and a spline portion 118 serving as afirst meshing portion provided on an outer periphery of the cylindricalportion 113. A plurality of spline grooves is formed in the splineportion 118 so as to be parallel to the rotation axis O.

The meshing member 2A integrally includes: a cylindrical portion 21; aflange portion 24 formed to overhang radially outwardly from afirst-rotational-member-11A-side end of the cylindrical portion 21; anda cylindrical spline portion 25 extending from an outer peripheral endof the flange portion 24 toward the first rotational member 11A. Aplurality of spline grooves is formed on an inner surface of the splineportion 25 so as to be parallel to the rotation axis O.

The spline portion 25 of the meshing member 2A is formed to have adiameter larger than the spline portion 118 of the first rotationalmember 11A. When the meshing member 2A moves axially toward the firstrotational member 11A, the spline portion 25 of the meshing member 2A ismeshed with the spline portion 118 of the first rotational member 11A,and hereby, the first rotational member 11A is connected to the secondrotational member 12 in a torque transmittable manner.

FIG. 8 is a perspective view illustrating the cam member 5 according tothe present embodiment. In that end of the cam member 5 which is on aside opposite to a base end surface 8 a thereof with which a rollingbearing 6 abuts, six sets of first to fourth locked portions 81 to 84 tobe locked by locking portions 19 are formed. When the cam member 5 isviewed clockwise from a direction of the rotation axis O, the first tofourth locked portions 81 to 84 in each set is configured such that thesecond locked portion 82 is formed adjacent to the first locked portion81, the third locked portion 83 is formed adjacent to the second lockedportion 82, and the fourth locked portion 84 is formed adjacent to thethird locked portion 83. A wall portion 85 projecting axially is formedin that end of the fourth locked portion 84 which is opposite to thethird locked portion 83.

The first to fourth locked portions 81 to 84 are placed at differentpositions in an axial direction of the cam member 5, and the secondlocked portion 82 is farther from the base end surface 8 a than thefirst locked portion 81, the third locked portion 83 is farther from thebase end surface 8 a than the second locked portion 82, and the fourthlocked portion 84 is farther from the base end surface 8 a than thethird locked portion 83.

Respective axial end surfaces 81 a to 84 a of the first to fourth lockedportions 81 to 84 are inclined with respect to a circumferentialdirection of the cam member 5. More specifically, the axial end surface81 a of the first locked portion 81 is inclined such that an end thereofon a second-locked portion-82 side is closer to the base end surface 8a, the axial end surface 82 a of the second locked portion 82 isinclined such that an end thereof on a third-locked portion-83 side iscloser to the base end surface 8 a, the axial end surface 83 a of thethird locked portion 83 is inclined such that an end thereof on afourth-locked portion-84 side is closer to the base end surface 8 a, andthe axial end surface 84 a of the fourth locked portion 84 is inclinedsuch that an end thereof on a wall-portion-85 side is closer to the baseend surface 8 a.

An axial end surface 85 a of the wall portion 85 is inclined in the samedirection as the axial end surfaces 81 a to 84 a. Further, one wallsurface 85 b of the wall portion 85 in its circumferential directionfaces the fourth locked portion 84.

FIGS. 9A to 9D are operation explanatory views each illustrating the cammember 5 according to the present embodiment and the armature 4 as wellas the locking portions 19. Note that, in FIGS. 9A to 9D, a secondhousing member 102 is omitted except for the plurality of lockingportions 19.

An operation of the cam member 5 and the armature 4 at the time when astate where the locking portion 19 locks the first locked portion 81 isshifted to a state where the locking portion 19 locks the second lockedportion 82 is the same as the operation described in the firstembodiment with reference to FIG. 5A and FIGS. 5C to 5E. That is, FIG.9A illustrates a first state where the locking portion 19 locks thefirst locked portion 81, and FIG. 9B illustrates a third state where thearmature 4 moves from a first position to a second position. Further,FIG. 9C illustrates a fourth state where the armature 4 is in the middleof returning to the first position from the second position, and FIG. 9Dillustrates a fifth state where the locking portion 19 locks the secondlocked portion 82.

In the present embodiment, since the cam member 5 includes four lockedportions (the first to fourth locked portions 81 to 84) placed atdifferent axial positions, current application to an electromagneticcoil 3 and stop of the current application thereto are performed threetimes. Hereby, the armature 4 reciprocates three times between the firstposition and the second position, so that the cam member 5 rotates froma position where the locking portion 19 locks the first locked portion81 to a position where the locking portion 19 locks the fourth lockedportion 84.

In a state where the locking portion 19 locks the first locked portion81 and the spline portion 25 of the meshing member 2A is not meshed withthe spline portion 118 of the first rotational member 11A, so that theelectromagnetic clutch device 1A is in an uncoupled state. Further, in astate where the locking portion 19 locks the fourth locked portion 84,the spline portion 25 of the meshing member 2A is meshed with the splineportion 118 of the first rotational member 11A, so that theelectromagnetic clutch device 1A is in a coupled state. A state wherethe locking portion 19 locks the second locked portion 82 and a statewhere the locking portion 19 locks the third locked portion 83 are anincompletely meshed state where part of an axial tip side of the splineportion 25 of the meshing member 2A is splined to the spline portion 118of the first rotational member 11A. That is, in the present embodiment,when the armature 4 repeats a movement from the first position to thesecond position several times, the spline portion 25 of the meshingmember 2A is meshed with the spline portion 118 of the first rotationalmember 11A.

FIG. 10 is a schematic view to describe an operation at the time when astate where the locking portion 19 locks the fourth locked portion 84 isshifted to a state where the locking portion 19 locks the first lockedportion 81, and the electromagnetic clutch device 1A switches over fromthe coupled state to the uncoupled state.

FIG. 10A illustrates a state where the locking portion 19 locks thefourth locked portion 84, and the armature 4 is placed in a firstposition. In this state, the locking portion 19 abuts with the axial endsurface 84 a of the fourth locked portion 84 and the circumferentialwall surface 85 b of the wall portion 85.

FIG. 10B illustrates a state where the armature 4 moves to a secondposition. In a course of a movement of the armature 4 from the firstposition to the second position, a pressing projection 41 thereofpresses and moves the cam member 5 toward the meshing member 2A. Due tothe movement of the cam member 5, a state where the locking portion 19abuts with the circumferential wall surface 85 b of the wall portion 85is released.

FIG. 10C illustrates a state where, due to sliding between the axial endsurface 84 a of the fourth locked portion 84 and a facing surface 41 aof the pressing projection 41 of the armature 4, the cam member 5rotates in an arrow-A direction only by a first predetermined angle. Dueto the rotation of the cam member 5, the circumferential wall surface 85b of the wall portion 85 abuts with a side surface 41 b of the pressingprojection 41 of the armature 4.

FIG. 10D illustrates a state where the armature 4 is in the middle ofreturning to the first position from the second position. In this state,a tip end surface 19 a of the locking portion 19 abuts with the axialend surface 85 a of the wall portion 85, and a rotational force towardthe arrow-A direction is applied to the cam member 5.

FIG. 10E illustrates a state where the armature 4 returns to the firstposition and the cam member 5 rotates in the arrow-A direction until thelocking portion 19 locks the first locked portion 81. In a course ofshifting from the state illustrated in FIG. 10C to the state illustratedin FIG. 10D, the cam member 5 is largely displaced in the axialdirection, so that meshing between the spline portion 25 of the meshingmember 2A and the spline portion 118 of the first rotational member 11Ais released.

According to the present embodiment, in addition to theoperation/working-effect described in the first embodiment, it ispossible to obtain the following effect. That is, by repeating severaltimes the axial movement of the armature 4, the meshing member 2A movesat stages in a direction where the meshing member 2A is meshed with thefirst rotational member 11A. Accordingly, even in a case where themeshing member 2A moves by a distance longer than a moving distance ofthe armature 4 (an axial moving distance between the first position andthe second position) so as to switch between the uncoupled state and thecoupled state, it is possible to mesh the meshing member 2A with thefirst rotational member 11A. Hereby, it is possible to increase ameshing length between the spline portion 25 of the meshing member 2Aand the spline portion 118 of the first rotational member 11A, therebymaking it possible to obtain a large torque transmission capacity.

Note that the present embodiment deals with a case where the cam member5 includes four locked portions (the first to fourth locked portions 81to 84) placed at different axial positions. However, if a plurality oflocked portions is formed in at least three different axial positions,it is possible to obtain the operation/working-effect of the presentembodiment.

The electromagnetic clutch devices 1, 1A of the present invention havebeen described above based on the first and second embodiments. However,the present invention is not limited to these embodiments, but isperformable in various modifications within a range which does notdeviate from the gist of the present invention. For example, it is alsopossible to use the electromagnetic clutch devices 1, 1A for purposesexcept for a purpose of transmitting a driving force of a vehicle.

FIG. 11 is a sectional view of an electromagnetic clutch deviceaccording to a third embodiment of the present invention and its vicinalarea.

An electromagnetic clutch device 1 in the present embodiment connects asecond rotational member 12 to a first rotational member 11B in a torquetransmittable manner. The second rotational member 12 and the firstrotational member 11B have a common rotation axis O so as to becoaxially supported by a housing 10 in a relatively rotatable manner.The housing 10 is constituted by a first housing member 101 and a secondhousing member 102, and the first housing member 101 and the secondhousing member 102 are fixed to each other via a plurality of bolts 103(only one bolt 103 is illustrated in FIG. 11).

The first rotational member 11B is rotatably supported by a ball bearing16 placed between the first rotational member 11B and the first housingmember 101. The first rotational member 11B integrally includes: a shaftportion 121 supported by the ball bearing 16; an overhanging portion 122formed to overhang radially outwardly from an end of the shaft portion121; a cylindrical portion 123 extending from an outer end of theoverhanging portion 122 toward the second rotational member 12 along therotation axis O; a flange portion 124 formed to overhang furtherradially outwardly from a tip end of the cylindrical portion 123; and aspline portion 125 formed in an outer periphery of the flange portion124.

The second rotational member 12 integrally includes: a cylindricalportion 110 having an insertion hole 11 a formed so that a shaft 100 tobe inserted from an opening 102 a formed in the second housing member102 passes therethrough; a flange portion 111 formed to overhangradially outwardly from an outer peripheral surface of the cylindricalportion 110; and a spline portion 112 serving as a first meshing portionformed in an outer periphery of the flange portion 111. An innerperipheral spline portion 11 b splined to an outer peripheral splineportion 100 a of the shaft 100 is formed on an inner surface of theinsertion hole 11 a. The second rotational member 12 and the shaft 100are connected so as to be non-rotatable relative to each other due tothe splining between the inner peripheral spline portion 11 b and theouter peripheral spline portion 100 a, and an axial relative movementthereof is regulated by a snap ring 100 c. A sealing member 100 d isprovided so as to seal between an outer peripheral surface of the shaft100 and an inner surface of the opening 102 a of the second housingmember 102.

That one end small-diameter portion 110 b of the second rotationalmember 12 which is provided on a first-rotational-member-11B-side end ofthe second rotational member 12 in its axial direction is supported by aball bearing 17 placed on an inner side of the cylindrical portion 123of the first rotational member 11B, and the other end small-diameterportion 110 c provided on that end of the second rotational member 12which is closer to the opening 102 a of the second housing member 102 issupported by a ball bearing 18 placed between the second rotationalmember 12 and the second housing member 102. A large diameter portion110 a having an outside diameter larger than the one end small-diameterportion 110 b and the other end small-diameter portion 110 c is formedbetween the one end small-diameter portion 110 b and the other endsmall-diameter portion 110 c, and a flange portion 111 is provided onthat end of the large diameter portion 110 a which is closer to the oneend small-diameter portion 110 b. The electromagnetic clutch device 1 isplaced between an outer peripheral surface of the second rotationalmember 12 and the housing 10.

The electromagnetic clutch device 1 includes: a meshing member 2Bconnected to the first rotational member 11B so as to be axially movablebut relatively non-rotatable relative to the first rotational member11B; an electromagnetic coil 3 for generating a magnetic force bycurrent application; an armature 4 to be axially moved due to themagnetic force of the electromagnetic coil 3; a biasing member 7 forbiasing the meshing member 2B axially; and a pressing mechanism 1 a forpressing the meshing member 2B against a biasing force of the biasingmember 7 by an axial movement of the armature 4 so as to move themeshing member 2B axially.

The meshing member 2B integrally includes: a cylindrical portion 21outwardly engaged with the large diameter portion 110 a in thecylindrical portion 110 of the second rotational member 12; a flangeportion 22 formed to overhang radially outwardly from that end of thecylindrical portion 21 which is closer to the flange portion 111 of thesecond rotational member 12; a cylindrical portion 23 extending from anouter end of the flange portion 22 toward the first rotational member11B along the rotation axis O; and a spline portion 24 formed in aninner periphery of the cylindrical portion 23 and serving as a secondmeshing portion.

That facing surface 22 a of the flange portion 22 of the meshing member2B which faces the flange portion 111 of the second rotational member 12and that facing surface 111 a of the flange portion 111 of the secondrotational member 12 which faces the flange portion 22 of the meshingmember 2B axially face each other via a gap in a coupled state of thesecond rotational member 12 and the first rotational member 11B asillustrated on a lower side relative to the rotation axis O in FIG. 11.In the present embodiment, the facing surfaces 111 a, 22 a are both flatplanes parallel to a radial direction of the rotation axis O, and whenthe meshing member 2B is pressed toward the first rotational member 11Bdue to an axial movement of the cam member 5 (as will be describedlater), the facing surface 22 a is pressed against the facing surface111 a so as to frictionally slide over the facing surface 111 a.

The spline portion 24 of the meshing member 2B is always meshed with thespline portion 125 provided in the first rotational member 11B, so thatits rotation relative to the first rotational member 11B is regulated.Further, due to an axial movement of the meshing member 2B in adirection where the meshing member 2B is distanced from the firstrotational member 11B, the spline portion 24 is meshed with the splineportion 112 provided in the second rotational member 12. When the splineportion 24 of the meshing member 2B is meshed with the spline portion125 of the first rotational member 11B and the spline portion 112 of thesecond rotational member 12, the second rotational member 12 isconnected to the first rotational member 11B in a torque transmittablemanner via the meshing member 2B. That is, the spline portion 24 of themeshing member 2B is always meshed with the first rotational member 11B,and when the meshing member 2B axially moves, the spline portion 24 isalso meshed with the second rotational member 12, and hereby, the secondrotational member 12 is connected to the first rotational member 11B ina torque transmittable manner.

An upper side relative to the rotation axis O in FIG. 11 illustrates astate (an uncoupled state) where the spline portion 24 of the meshingmember 2B is not meshed with the spline portion 112 of the secondrotational member 12, and a lower side relative to the rotation axis Oin FIG. 11 illustrates a state (a coupled state) where the splineportion 24 of the meshing member 2B is meshed with the spline portion112 of the second rotational member 12.

A biasing member 7 biases the meshing member 2B in a direction where thespline portion 24 of the meshing member 2B is meshed with the splineportion 112 of the second rotational member 12. In the presentembodiment, the biasing member 7 is constituted by a plurality of coneddisc springs 70 arranged along a direction of the rotation axis O.However, the biasing member 7 may be constituted by an elastic body suchas a coil spring or a rubber. Further, an axial one end of the biasingmember 7 along the rotation axis O abuts with a snap ring 75 fitted toan outer periphery of the cylindrical portion 123 of the firstrotational member 11B, and the other axial end thereof abuts with anaxial end surface 23 a of the cylindrical portion 23 of the meshingmember 2B, so that the cylindrical portion 23 of the meshing member 2Bis pressed toward the flange portion 111 of the second rotational member12.

The electromagnetic coil 3 is formed by winding, around a bobbin 31 madefrom resin, a winding 32 through which a current supplied from acontroller (not shown) flows. The electromagnetic coil 3 is held by anannular yoke 30 made from a ferromagnetic material such as iron, and theyoke 30 is supported by the second housing member 102. The yoke 30 has aplurality of holes 30 a to which columnar pins 300 placed in parallelwith the rotation axis O are fitted, and one ends of the pins 300 areinserted into the holes 30 a. Further, the second housing member 102 hasa plurality of holes 102 b to which the other ends of the pins 300 arefitted.

FIG. 12 is a perspective view illustrating the armature 4. The armature4 integrally includes: an annular-disk shaped main body 40 having, inits center, a through hole 4 a through which the second rotationalmember 12 passes; and a plurality of (six in the present embodiment)pressing projections 41 projecting from an inner peripheral surface ofthe through hole 4 a toward the center of the main body 40. In the mainbody 40, pin insertion holes 4 b through which a plurality of pins 300(illustrated in FIG. 11) passes are formed at several places (fourplaces in the present embodiment) around the through hole 4 a. Thatfacing surface 41 a of the pressing projection 41 which is opposed toaxial end surfaces 51 a to 54 a of first to fourth locked portions 51 to54 of the cam member 5 (described later) is formed as an inclinedsurface that is inclined with respect to a thickness direction (adirection parallel to the rotation axis O) of the main body 40.

As illustrated in FIG. 11, the armature 4 is elastically pressed in adirection to be distanced from the yoke 30, by a coned disc spring 301placed between the main body 40 and the yoke 30. When no current isapplied to the electromagnetic coil 3, the armature 4 abuts with areceiving portion 102 c of the second housing member 102 due to apressing force of the coned disc spring 301, and when a current isapplied to the electromagnetic coil 3, the armature 4 is drawn to theyoke 30 by a magnetic force thereof. Further, a rotation of the armature4 relative to the second housing member 102 and the yoke 30 is regulatedby the plurality of pins 300 passing through the pin insertion holes 4b. Accordingly, the armature 4 is guided by the plurality of pins 300 soas to move between a first position in which the armature 4 abuts withthe receiving portion 102 c of the second housing member 102 and asecond position in which the armature 4 comes close to the yoke 30. Theupper side relative to the rotation axis O in FIG. 11 illustrates astate where the armature 4 is placed in the second position, and thelower side relative to the rotation axis O in FIG. 11 illustrates astate where the armature 4 is placed in the first position.

The pressing mechanism 1 a includes a locking portion 19 provided so asto be axially immovable relative to the second rotational member 12 andrelatively non-rotatable relative to the armature 4; and a cylindricalcam member 5 including a plurality of locked portions (theafter-mentioned first to fourth locked portions 51 to 54) to be lockedby the locking portion 19 at different axial positions. The pressingmechanism 1 a is configured such that, in response to an axial movementof the armature 4, the locking portion 19 locks that another lockedportion out of the plurality of locked portions which is placed at adifferent axial position.

The cam member 5 is outwardly engaged with the large diameter portion110 a in the cylindrical portion 110 of the second rotational member 12,as well as the meshing member 2B. The meshing member 2B and the cammember 5 are loosely fitted to the cylindrical portion 110 of the secondrotational member 12, and are axially movable and relatively rotatablerelative to the second rotational member 12. A rolling bearing 6 isplaced between the meshing member 2B and the cam member 5. In thepresent embodiment, the rolling bearing 6 is constituted by a needlethrust roller bearing. The meshing member 2B is placed closer to thefirst rotational member 11B than the rolling bearing 6, and the cammember 5 is placed closer to the locking portion 19 than the rollingbearing 6.

The cam member 5 receives a pressing force of the biasing member 7 as anaxial biasing force toward a plurality of locking portions 19 from themeshing member 2B via the rolling bearing 6. In the present embodiment,the plurality of locking portions 19 is formed integrally with thesecond housing member 102, but the plurality of locking portions 19 maybe formed separately from the second housing member 102.

In response to the axial movement of the armature 4, the cam member 5presses the meshing member 2B axially along the rotation axis O in adirection where the meshing between the spline portion 24 of the meshingmember 2B and the spline portion 112 of the second rotational member 12is released.

FIG. 13 is a perspective view illustrating the plurality of lockingportions 19 provided in the second housing member 102.

The second housing member 102 has a through hole 102 d through which thesecond rotational member 12 passes, and the plurality of lockingportions 19 projects from an inner peripheral surface of the throughhole 102 d toward the second rotational member 12, and also projectstoward the cam member 5 along the rotation axis O. The plurality oflocking portions 19 is provided at regular intervals along acircumferential direction of the through hole 102 d, and the number ofthe locking portions 19 is the same as the number of the pressingprojections 41 of the armature 4. Similarly to the facing surface 41 aof the pressing projection 41 of the armature 4, the locking portion 19is formed such that that tip end surface 19 a of the locking portion 19which is opposed to the axial end surfaces 51 a to 54 a of the lockedportions 51 to 54 of the cam member 5 (described later) is formed as aninclined surface that is inclined with respect to the direction parallelto the rotation axis O.

FIG. 14 is a perspective view illustrating the cam member 5. In the cammember 5, a plurality of locked portions to be locked by the lockingportion 19 at different axial positions is formed so as to be adjacentto each other in a circumferential direction. In the present embodiment,the plurality of locked portions is constituted by first to fourthlocked portions 51 to 54. In an end opposite to a base end surface 5 awith which the rolling bearing 6 abuts, six sets of the first to fourthlocked portions 51 to 54 are formed along the circumferential direction.

When the cam member 5 is viewed clockwise from a direction of therotation axis O, the first to fourth locked portions 51 to 54 in eachset is configured such that the second locked portion 52 is formedadjacent to the first locked portion 51, the third locked portion 53 isformed adjacent to the second locked portion 52, and the fourth lockedportion 54 is formed adjacent to the third locked portion 53. A wallportion 55 projecting axially is formed in that end of the fourth lockedportion 54 which is opposite to the third locked portion 53.

The first to fourth locked portions 51 to 54 are placed at differentpositions in an axial direction of the cam member 5. The second lockedportion 52 is farther from the base end surface 5 a than the firstlocked portion 51, the third locked portion 53 is farther from the baseend surface 5 a than the second locked portion 52, and the fourth lockedportion 54 is farther from the base end surface 5 a than the thirdlocked portion 53.

Respective axial end surfaces 51 a to 54 a of the first to fourth lockedportions 51 to 54 are inclined with respect to the circumferentialdirection of the cam member 5. More specifically, the axial end surface51 a of the first locked portion 51 is inclined such that an end thereofon a second-locked portion-52 side is closer to the base end surface 5a, the axial end surface 52 a of the second locked portion 52 isinclined such that an end thereof on a third-locked portion-53 side iscloser to the base end surface 5 a, the axial end surface 53 a of thethird locked portion 53 is inclined such that an end thereof on afourth-locked portion-54 side is closer to the base end surface 5 a, andthe axial end surface 54 a of the fourth locked portion 54 is inclinedsuch that an end thereof on a wall-portion-55 side is closer to the baseend surface 5 a.

An axial end surface 55 a of the wall portion 55 is inclined in the samedirection as the axial end surfaces 51 a to 54 a. Further, one sidesurface of 55 b of the wall portion 55 in its circumferential directionfaces the fourth locked portion 54.

The facing surface 41 a of the pressing projection 41 of the armature 4and the tip end surface 19 a of the locking portion 19 abut with theaxial end surfaces 51 a to 54 a of the first to fourth locked portions51 to 54. The facing surface 41 a of the armature 4 abuts with outerparts of the axial end surfaces 51 a to 54 a in a radial direction ofthe cam member 5, and the tip end surface 19 a of the locking portion 19abuts with inner parts of the axial end surfaces 51 a to 54 a in theradial direction of the cam member 5. The cam member 5 receives, due tothe biasing member 7, an axial biasing force at which the axial endsurfaces 51 a to 54 a are pressed against the pressing projection 41 ofthe armature 4 and the locking portion 19.

When the locking portion 19 locks the first locked portion 51, adistance between the tip end surface 19 a of the locking portion 19 andthe base end surface 5 a is shortest. Further, when the locking portion19 locks the fourth locked portion 54, the distance between the tip endsurface 19 a of the locking portion 19 and the base end surface 5 a islongest.

When the locking portion 19 locks the first locked portion 51, thespline portion 24 of the meshing member 2B is meshed with the splineportion 112 of the second rotational member 12, as illustrated on thelower side relative to the rotation axis O in FIG. 11. When the lockingportion 19 locks the fourth locked portion 54, the meshing between thespline portion 24 of the meshing member 2B and the spline portion 112 ofthe second rotational member 12 is released, as illustrated on the upperside relative to the rotation axis O in FIG. 11. In a state where thelocking portion 19 locks the second locked portion 52 or the thirdlocked portion 53, the spline portion 24 of the meshing member 2B ismeshed with part of the spline portion 112 of the second rotationalmember 12.

Next will be described an operation of the pressing mechanism 1 a withreference to FIGS. 15 and 16.

FIGS. 15A to 15D are perspective views each illustrating the armature 4and the cam member 5 without illustrating the second housing member 102except for the plurality of locking portions 19. FIGS. 16A to 16D areschematic views each illustrating a state where the cam member 5 isviewed from an outside thereof in a radial direction, together with thepressing projection 41 of the armature 4 and the locking portion 19.

FIGS. 15A and 16A illustrate a first state where the locking portion 19locks the first locked portion 51 and the armature 4 is placed in afirst position. In the first state, the axial end surface 51 a of thefirst locked portion 51 is pressed against the tip end surface 19 a ofthe locking portion 19 by a biasing force of the biasing member 7, andis also opposed to the facing surface 41 a of the pressing projection 41of the armature 4. Further, the locking portion 19 abuts with acircumferential side surface 51 b of the first locked portion 51, andthe pressing projection 41 of the armature 4 is opposed to the axial endsurface 51 a in a position distanced from the side surface 51 b in thecircumferential direction of the cam member 5. The side surface 51 b ofthe first locked portion 51 is a stepped surface formed between thefirst locked portion 51 and the second locked portion 52, and is a flatplane parallel to the axial direction of the cam member 5. An angleformed between the axial end surface 51 a and the side surface 51 b inthe first locked portion 51 is an acute angle.

FIGS. 15B and 16B illustrate a second state where a current is appliedto the electromagnetic coil 3 and the armature 4 moves to a secondposition from the first state illustrated in FIGS. 15A and 16A. Thefacing surface 41 a of the pressing projection 41 of the armature 4abuts with the axial end surface 51 a in a course of shifting from thefirst state to the second state, and the pressing projection 41 pressesthe cam member 5 toward the meshing member 2B. Further, in the secondstate, an abutting state of the locking portion 19 with respect to theside surface 51 b of the first locked portion 51 is released, and due tosliding between the axial end surface 51 a of the first locked portion51 and the facing surface 41 a of the pressing projection 41 of thearmature 4, the cam member 5 rotates in an arrow-A direction only by afirst predetermined angle. Due to the rotation of the cam member 5, theside surface 51 b of the first locked portion 51 abuts with a sidesurface 41 b of the pressing projection 41 of the armature 4.

That is, when the armature 4 axially moves from the first position tothe second position, the armature 4 performs a pressing operation topress the cam member 5 toward the meshing member 2B so as to move thecam member 5 toward the meshing member 2B and to rotate the cam member 5only by the first predetermined angle. The first predetermined angle isan angle corresponding to a distance d1 of a gap between the pressingprojection 41 of the armature 4 and the side surface 51 b of the firstlocked portion 51, as illustrated in FIG. 16A.

When the armature 4 is placed in the second position, the tip endsurface 19 a of the locking portion 19 is opposed to the axial endsurface 52 a via a gap between the tip end surface 19 a and the secondlocked portion 52. That is, when the armature 4 moves to the secondposition, the cam member 5 rotates by the first predetermined angle, thepressing projection 41 abuts with the side surface 51 b, and the tip endsurface 19 a of the locking portion 19 is opposed to the axial endsurface 52 a of the second locked portion 52 adjacent to the firstlocked portion 51.

FIGS. 15C and 16C illustrate a third state where current application tothe electromagnetic coil 3 is stopped and the armature 4 is in themiddle of returning to the first position from the second position. Inthe third state, the tip end surface 19 a of the locking portion 19abuts with the axial end surface 52 a of the second locked portion 52.When the tip end surface 19 a of the locking portion 19 abuts with theaxial end surface 52 a of the second locked portion 52, a rotationalforce toward the arrow-A direction is applied to the cam member 5, butthe rotation of the cam member 5 to the arrow-A direction is regulatedby the abutment of the side surface 41 b of the pressing projection 41of the armature 4 with respect to the side surface 51 b of the firstlocked portion 51.

FIGS. 15D and 16D illustrate a fourth state where the armature 4 returnsto the first position, and the cam member 5 rotates in the arrow-Adirection until a circumferential side surface 52 b of the second lockedportion 52 abuts with a side surface 19 b of the locking portion 19. Inthe fourth state, due to sliding between the tip end surface 19 a of thelocking portion 19 and the axial end surface 52 a of the second lockedportion 52 of the cam member 5 that receives a biasing force of thebiasing member 7, the cam member 5 rotates relative to the lockingportion 19 by a second predetermined angle. Hereby, the locking portion19 locks the second locked portion 52. The second predetermined angle isan angle corresponding to a distance d2 between the side surface 52 b ofthe second locked portion 52 and the locking portion 19 in the thirdstate illustrated in FIG. 16C. That is, when the armature 4 moves fromthe second position to the first position, the cam member 5 furtherrotates only by the second predetermined angle, and hereby, the lockingportion 19 locks the second locked portion 52 adjacent to the firstlocked portion 51.

The pressing mechanism 1 a is configured such that, when the armature 4reciprocates between the first position and the second position severaltimes, the cam member 5 axially moves the meshing member 2B against thebiasing force of the biasing member 7. In the present embodiment, fourlocked portions (the first to fourth locked portions 51 to 54) formed inthe cam member 5 in a stepped manner are provided. In view of this, whencurrent application to the electromagnetic coil 3 and stop of thecurrent application thereto are performed three times so that thearmature 4 reciprocates between the first position and the secondposition three times, the cam member 5 rotates from a position where thelocking portion 19 locks the first locked portion 51 to a position wherethe locking portion 19 locks the fourth locked portion 54.

When a distance from the base end surface 5 a to the axial end surface51 a of the first locked portion 51 is taken as a distance d3 and adistance from the base end surface 5 a to the axial end surface 54 a ofthe fourth locked portion 54 is taken as a distance d4 as illustrated inFIG. 16A, the distance d4 is longer than the distance d3, and the cammember 5 reciprocates axially within a range corresponding to adifference between the distance d4 and the distance d3.

FIGS. 17A to 17D are schematic views to describe an operation at thetime when a state where the locking portion 19 locks the fourth lockedportion 54 is shifted to a state where the locking portion 19 locks thefirst locked portion 51, so that the electromagnetic clutch device 1switches over from the uncoupled state to the coupled state.

FIG. 17A illustrates a state where the locking portion 19 locks thefourth locked portion 54 and the armature 4 is placed in the firstposition. In this state, the locking portion 19 abuts with the axial endsurface 54 a of the fourth locked portion 54 and a circumferential sidesurface 55 b of the wall portion 55.

FIG. 17B illustrates a state where the armature 4 moves to the secondposition. In a course of a movement of the armature 4 from the firstposition to the second position, the pressing projection 41 presses andmoves the cam member 5 toward the meshing member 2B due to a pressingoperation. At this time, as illustrated on the upper side relative tothe rotation axis O in FIG. 11, that facing surface 22 a of the flangeportion 22 of the meshing member 2B is axially pressed against thefacing surface 111 a of the flange portion 111 of the second rotationalmember 12. Hereby, in a case where the second rotational member 12 andthe first rotational member 11B rotate relative to each other with arotation speed difference, the facing surfaces 22 a, 111 a frictionallyslide over each other, thereby causing a friction torque thatsynchronizes the rotation of the second rotational member 12 with therotation of the first rotational member 11B.

More specifically, the friction torque is caused when the facing surface22 a of the flange portion 22 of the meshing member 2B is pressedagainst the facing surface 111 a of the flange portion 111 of the secondrotational member 12 due to the axial movement of the cam member 5 alongwith the pressing operation of the armature 4. That is, the armature 4performs the pressing operation to press the cam member 5 before thelocking portion 19 locks the first locked portion 51, so as to cause thefriction torque to reduce the rotation speed difference between thesecond rotational member 12 and the first rotational member 11B.

Further, when the state where the locking portion 19 abuts with thecircumferential side surface 55 b of the wall portion 55 is released bythe pressing operation, the cam member 5 rotates in the arrow-Adirection only by the first predetermined angle.

The facing surface 111 a of the flange portion 111 of the secondrotational member 12 is one aspect of a “first friction surface on asecond rotational member side” of the present invention, and the facingsurface 22 a of the flange portion 22 of the meshing member 2B is oneaspect of a “second friction surface on a first rotational member side”of the present invention. Here, the “first friction surface on thesecond rotational member side” includes a friction surface formed in amember provided so as to rotate integrally with the second rotationalmember 12 as well as a friction surface formed in the second rotationalmember 12, and the “second friction surface on the first rotationalmember side” includes a friction surface formed in a member (the meshingmember 2B) provided so as to rotate integrally with the first rotationalmember 11B as well as a friction surface formed in the first rotationalmember 11B. For example, a first friction surface formed in a memberprovided so as to be non-rotatable relative to the second rotationalmember 12, and a second friction surface formed in the first rotationalmember 11B frictionally slide over each other so as to cause a frictiontorque.

FIG. 17C illustrates a state where the armature 4 is in the middle ofreturning to the first position from the second position. In this state,the tip end surface 19 a of the locking portion 19 abuts with the axialend surface 55 a of the wall portion 55, and a rotational force towardthe arrow-A direction is applied to the cam member 5.

FIG. 17D illustrates a state where the armature 4 returns to the firstposition and the locking portion 19 rotates in the arrow-A direction tolock the first locked portion 51. In a course of shifting from the stateillustrated in FIG. 17C to the state illustrated in FIG. 17D, the cammember 5 is largely displaced in the axial direction throughout therange corresponding to the difference between the distance d3 and thedistance d4, so that the spline portion 24 of the meshing member 2B ismeshed with the spline portion 112 of the second rotational member 12.

As such, when the cam member 5 axially moves in a direction opposite toa direction where the armature 4 axially moves due to a magnetic force,the spline portion 24 of the meshing member 2B is meshed with the splineportion 112 of the second rotational member 12 due to the biasing forceof the biasing member 7. More specifically, when the locking of thelocking portion 19 with respect to the fourth locked portion 54 formedin a position farthest from the meshing member 2B among the first tofourth locked portions 51 to 54 is released and the locking portion 19locks the first locked portion 51 formed in a position nearest to themeshing member 2B, the spline portion 24 is meshed with the splineportion 112 of the second rotational member 12 due to the biasing forceof the biasing member 7, so as to cause the coupled state where thesecond rotational member 12 is connected to the first rotational member11B in a torque transmittable manner.

That is, when the coupled state between the second rotational member 12and the first rotational member 11B is shifted to the uncoupled state,it is necessary for the armature 4 to reciprocate between the firstposition and the second position three times. However, when theuncoupled state is shifted to the coupled state, the armature 4reciprocates between the first position and the second position onlyonce.

According to the embodiment described above, it is possible to obtainthe following operation/working-effect.

The meshing member 2B moves axially along with the axial movement of thearmature 4 from the first position to the second position so as to bemeshed with the first rotational member 11B. Accordingly, in comparisonwith a case where an electric motor and a speed reducer are used as anactuator for operating a clutch device, for example, it is possible toperform switching between the coupled state and the uncoupled stateimmediately. That is, responsiveness of switching improves.

In the electromagnetic clutch device 1, in a course of shifting from theuncoupled state between the second rotational member 12 and the firstrotational member 11B to the coupled state, the facing surface 22 a ofthe flange portion 22 of the meshing member 2B is axially pressedagainst the facing surface 111 a of the flange portion 111 of the secondrotational member 12, thereby causing a friction torque thatsynchronizes the rotation of the second rotational member 12 with therotation of the first rotational member 11B. Accordingly, in comparisonwith a case where no friction torque is caused, the spline portion 24 ofthe meshing member 2B is smoothly meshed with the spline portion 112 ofthe second rotational member 12. This makes it possible to performswitching from the uncoupled state to the coupled state immediately, andresponsiveness of the switching from the uncoupled state to the coupledstate improves. Further, by causing the armature 4 to reciprocatebetween the first position and the second position once from the statewhere the locking portion 19 locks the fourth locked portion 54, thespline portion 24 is meshed with the spline portion 112 of the secondrotational member 12 due to the biasing force of the biasing member 7.This makes it possible to sufficiently improve responsiveness of theswitching from the uncoupled state to the coupled state.

Since the axial end surfaces 51 a to 54 a of the first to fourth lockedportions 51 to 54 of the cam member 5 are inclined with respect to thecircumferential direction, the axial end surfaces 51 a to 54 a slideover the facing surface 41 a of the pressing projection 41 due to theaxial movement of the armature 4 from the first position to the secondposition, and thus, the cam member 5 rotates only by the firstpredetermined angle. Further, when the armature 4 axially moves from thesecond position to the first position, the cam member 5 rotates by thesecond predetermined angle due to the inclination of the axial endsurfaces 51 a to 54 a. That is, since the cam member 5 rotates due tothe axial movement of the armature 4, it is possible to sequentiallyswitch respective locking states of the locking portion 19 with respectto the first to fourth locked portions 51 to 54 from one to another,without any rotational drive mechanism such as a motor for rotating thecam member 5. This makes it possible to downsize the electromagneticclutch device 1 and to reduce cost thereof.

The biasing member 7 is placed between the first rotational member 11Band the meshing member 2B, so that the meshing member 2B is biased by abiasing force thereof toward the second rotational member 12, and thecam member 5 is pressed, via the rolling bearing 6, toward the lockingportion 19 and the pressing projection 41 of the armature 4. Hereby, thespline portion 24 of the meshing member 2B is immediately meshed withthe spline portion 112 of the second rotational member 12 at the timewhen the locking portion 19 locks the first locked portion 51. Further,sliding of the axial end surfaces 51 a to 54 a of the first to fourthlocked portions 51 to 54 and the axial end surface 55 a of the wallportion 55 with respect to the facing surface 41 a of the pressingprojection 41 and the tip end surface 19 a of the locking portion 19allows the cam member 5 to rotate.

In a state where the locking portion 19 locks the first locked portion51 of the cam member 5 and current application to the electromagneticcoil 3 is stopped, the meshing member 2B is meshed with the secondrotational member 12. Accordingly, it is not necessary to continue thecurrent application to the electromagnetic coil 3 in the coupled state.This makes it possible to reduce power consumption and heat generationat the time of the operation of the electromagnetic clutch device 1.

The cam member 5 includes the first to fourth locked portions 51 to 54placed at different axial positions, and is axially movable within arange corresponding to an axial distance between the fourth lockedportion 54 formed in a position farthest from the meshing member 2B andthe first locked portion 51 formed in a position nearest to the meshingmember 2B. This makes it possible to increase an axial length of themeshing between the spline portion 24 of the meshing member 2B and thespline portion 112 of the second rotational member 12. This makes itpossible to transmit a large torque such as a driving force of thevehicle, for example.

When the cam member 5 axially moves in a direction opposite to adirection where the armature 4 axially moves due to a magnetic force,the spline portion 24 of the meshing member 2B is meshed with the splineportion 112 of the second rotational member 12. That is, a directionwhere the biasing member 7 biases the meshing member 2B is the same as adirection where the coned disc spring 301 biases the armature 4.Accordingly, at the time when the spline portion 24 of the meshingmember 2B is meshed with the spline portion 112 of the second rotationalmember 12 due to the biasing force of the biasing member 7, a biasingforce of the coned disc spring 301 does not disturb the movement of themeshing member 2B. This makes it possible to improve responsiveness ofthe switching from the uncoupled state to the coupled state.

Note that the present embodiment deals with a case where the cam member5 includes four locked portions (the first to fourth locked portions 51to 54) placed at different positions in the axial direction thereof.However, if a plurality of locked portions is formed in at least threedifferent positions in the axial direction, it is possible to obtain theoperation/working-effect of the present embodiment.

Next will be described a fourth embodiment of the present invention withreference to FIG. 18. FIG. 18 is an enlarged view illustrating anessential part of a meshing member 2B, a second rotational member 12,and a first rotational member 11B according to the fourth embodiment.Note that, similarly to FIG. 11, an upper side relative to a rotationaxis O in FIG. 18 illustrates an uncoupled state, and a lower siderelative to the rotation axis O in FIG. 18 illustrates a coupled state.Further, in the fourth embodiment, a constituent having the samefunction as that of a constituent described in the third embodiment hasthe same reference sign as the constituent in the third embodiment, anda redundant description thereof is omitted.

The present embodiment is different from the third embodiment in termsof shapes of a second rotational member 12, a first rotational member11B, and a meshing member 2B.

A flange portion 111 of the second rotational member 12 according to thepresent embodiment is provided with a rib portion 113 formed so as toproject from an outer end of the flange portion 111 toward a firstrotational member in a direction parallel to the rotation axis O. Aspline portion 112 is formed in an outer periphery of the rib portion113. Further, an outer peripheral surface 111 b of the flange portion111 is inclined with respect to the direction parallel to the rotationaxis O, and is formed as a tapered surface of which an outside diameteris gradually increased from a side closer to a flange portion 22 of themeshing member 2B toward a side closer to the spline portion 112.

Further, the first rotational member 11B according to the presentembodiment is provided with a cylindrical small-diameter tubular portion126 formed so as to project toward the flange portion 111 inside the ribportion 113 of the second rotational member 12 and to have an outsidediameter smaller than a cylindrical portion 123.

Furthermore, a shape of a cylindrical portion 23 of the meshing member2B according to the present embodiment is different from that of thethird embodiment, and a swelling portion 231 swelling radially inwardlyis formed in a flange-portion-22-side end of the cylindrical portion 23.An inner peripheral surface 231 a of the swelling portion 231 is formedas a tapered surface inclined with respect to the rotation axis O so asto face an outer peripheral surface 111 b of the flange portion 111 ofthe second rotational member 12 in a parallel manner.

In the present embodiment, in a course of shifting from the uncoupledstate to the coupled state as described in the third embodiment withreference to FIG. 17, when an armature 4 performs a pressing operationto press a cam member 5 toward the meshing member 2B, the innerperipheral surface 231 a of the swelling portion 231 of the meshingmember 2B is pressed against the outer peripheral surface 111 b of theflange portion 111 of the second rotational member 12 due to an axialmovement of the cam member 5, so that the inner peripheral surface 231 africtionally slides over the outer peripheral surface 111 b, therebycausing a friction torque. The friction torque synchronizes a rotationof the second rotational member 12 with a rotation of the firstrotational member 11B. The outer peripheral surface 111 b of the flangeportion 111 of the second rotational member 12 is one aspect of thefirst friction surface of the present invention, and the innerperipheral surface 231 a of the swelling portion 231 of the meshingmember 2B is one aspect of the second friction surface of the presentinvention.

Note that, in the present embodiment, at the time when the outerperipheral surface 111 b of the flange portion 111 of the secondrotational member 12 frictionally slides over the inner peripheralsurface 231 a of the swelling portion 231 of the meshing member 2B, afacing surface 111 a of the flange portion 111 of the second rotationalmember 12 does not make contact with a facing surface 22 a of the flangeportion 22 of the meshing member 2B. That is, a pressing force by thepressing operation of the armature 4 is received such that the innerperipheral surface 231 a of the swelling portion 231 of the meshingmember 2B abuts with the outer peripheral surface 111 b of the flangeportion 111 of the second rotational member 12.

According to the fourth embodiment, the outer peripheral surface 111 bof the flange portion 111 of the second rotational member 12 and theinner peripheral surface 231 a of the swelling portion 231 of themeshing member 2B that frictionally slide over each other are formed astapered surfaces. Accordingly, in addition to theoperation/working-effect similar to the third embodiment, a contactpressure that the outer peripheral surface 111 b (the first frictionsurface) of the flange portion 111 of the second rotational member 12receives from the inner peripheral surface 231 a (the second frictionsurface) of the swelling portion 231 of the meshing member 2B isincreased in comparison with the third embodiment. This makes itpossible to further increase the friction torque, thereby resulting inthat responsiveness of switching from the uncoupled state to the coupledstate is further improved.

Next will be described a fifth embodiment of the present invention withreference to FIG. 19. FIG. 19 is an enlarged view illustrating anessential part of a meshing member 2B, a second rotational member 13,and a first rotational member 11B according to the fifth embodiment.Note that, similarly to FIGS. 11 and 18, an upper side relative to arotation axis O in FIG. 19 illustrates an uncoupled state, and a lowerside relative to the rotation axis O in FIG. 19 illustrates a coupledstate. Further, in the fifth embodiment, a constituent having the samefunction as that of a constituent described in the third or fourthembodiment has the same reference sign as the constituent in the thirdor fourth embodiment, and a redundant description thereof is omitted.

The second rotational member 13 according to the fifth embodiment isdifferent from the second rotational member 12 according to the fourthembodiment in terms of a shape, and is configured to include acylindrical fixing member 130, and a moving member 131 projectingradially outwardly from an outer peripheral surface of the secondrotational member 13. The moving member 131 is provided so as to beaxially movable but relatively non-rotatable relative to the fixingmember 130. The moving member 131 is also axially movable relative tothe first rotational member 11B along the rotation axis O.

An inner peripheral spline portion 130 a splined to an outer peripheralspline portion 100 a of a shaft 100 is formed on an inner peripheralsurface of the fixing member 130. The inner peripheral spline portion130 a of the fixing member 130 is splined to the outer peripheral splineportion 100 a of the shaft 100 so that their relative rotation isregulated, and an axial relative movement of the fixing member 130 isregulated by a snap ring 100 c. Thus, the fixing member 130 is fixed tothe shaft 100.

Further, an outer peripheral spline portion 130 b is formed on an outerperipheral surface of the fixing member 130 along the rotation axis O.The outer peripheral spline portion 130 b is provided with a lockingprojection 130 c for restricting a range of an axial movement of themoving member 131, in one place on the outer peripheral spline portion130 b in its axial direction.

The moving member 131 integrally includes: a cylindrical portion 132provided with an inner peripheral spline portion 132 a splined to theouter peripheral spline portion 130 b of the fixing member 130; acircular plate portion 133 having an annular disk shape and extendingradially outwardly from a first-rotational-member-11B-side end of thecylindrical portion 132; a rib portion 134 projecting from an outer endof the circular plate portion 133 toward the first rotational member 11Bin a direction parallel to the rotation axis O; and a spline portion 135formed in an outer periphery of the rib portion 134.

The moving member 131 is axially movable but relatively non-rotatablerelative to the fixing member 130 due to splining between the innerperipheral spline portion 132 a and the outer peripheral spline portion130 b of the fixing member 130. Further, when the cylindrical portion132 is locked by the locking projection 130 c, an axial movement of themoving member 131 toward a cam member 5 is regulated.

When the spline portion 135 of the moving member 131 is splined to thespline portion 125 of the meshing member 2B, the second rotationalmember 13 is connected to the first rotational member 11B in a torquetransmittable manner.

An outer peripheral surface 133 b of the circular plate portion 133 isinclined with respect to the direction parallel to the rotation axis O,and is formed as a tapered surface of which an outside diameter isgradually increased from a side closer to a flange portion 22 of themeshing member 2B toward a side closer to the spline portion 135.Further, an inner peripheral surface 134 a of the rib portion 134 isinclined with respect to the direction parallel to the rotation axis O,and is formed as a tapered surface of which an inside diameter isgradually decreased toward the circular plate portion 133.

Further, in the present embodiment, an outer peripheral surface 126 a ofa small-diameter tubular portion 126 of the first rotational member 11Bis formed as a tapered surface facing the inner peripheral surface 134 aof the rib portion 134 of the moving member 131 in a parallel manner.

In the present embodiment, in a course of shifting from the uncoupledstate to the coupled state as described in the third embodiment withreference to FIG. 17, when an armature 4 performs a pressing operationto press the cam member 5 toward the meshing member 2B, an innerperipheral surface 231 a of a swelling portion 231 is pressed againstthe outer peripheral surface 133 b of the circular plate portion 133 dueto an axial movement of the meshing member 2B. Further, when the outerperipheral surface 133 b of the circular plate portion 133 receives apressing force at this time, the moving member 131 axially moves towardthe first rotational member 11B, so that the inner peripheral surface134 a of the rib portion 134 is pressed against the outer peripheralsurface 126 a of the small-diameter tubular portion 126 of the firstrotational member 11B.

Hereby, in a case where the armature 4 performs the pressing operationat the time when the second rotational member 12 and the firstrotational member 11B rotate relative to each other with a rotationalspeed difference, the inner peripheral surface 231 a of the swellingportion 231 of the meshing member 2B frictionally slides over the outerperipheral surface 133 b of the circular plate portion 133 of the movingmember 131, and the inner peripheral surface 134 a of the rib portion134 of the moving member 131 frictionally slides over the outerperipheral surface 126 a of the small-diameter tubular portion 126 ofthe first rotational member 11B, thereby causing a friction torque thatsynchronizes the rotation of the second rotational member 12 with therotation of the first rotational member 11B.

The outer peripheral surface 133 b of the circular plate portion 133 ofthe moving member 131 and the inner peripheral surface 134 a of the ribportion 134 are one aspect of the first friction surface of the presentinvention. Further, the inner peripheral surface 231 a of the swellingportion 231 of the meshing member 2B and the outer peripheral surface126 a of the small-diameter tubular portion 126 of the first rotationalmember 11B are one aspect of the second friction surface of the presentinvention.

According to the fifth embodiment, a friction torque is also causedbetween the inner peripheral surface 134 a of the rib portion 134 of themoving member 131 and the outer peripheral surface 126 a of thesmall-diameter tubular portion 126 of the first rotational member 11B.Accordingly, in addition to the operation/working-effect similar to thefourth embodiment, it is possible to further increase the frictiontorque in comparison with the fourth embodiment, thereby making itpossible to further improve responsiveness of switching from theuncoupled state to the coupled state.

Next will be described a sixth embodiment of the present invention withreference to FIGS. 20 to 24. In FIGS. 20 to 24, a constituent havingsubstantially the same function as that of a constituent described inthe third embodiment has the same reference sign as in the thirdembodiment, and a redundant description thereof is omitted.

FIG. 20 is a sectional view of an electromagnetic clutch device 1Baccording to the present embodiment and its vicinal area. In the thirdto fifth embodiments, the second rotational member 12, 13 is splined tothe shaft 100 in a relatively non-rotatable manner, and the firstrotational member 11B is connected to the second rotational member 12,13 by the electromagnetic clutch device 1 in a torque transmittablemanner. However, in the present embodiment, a second rotational member14 is splined to a shaft 100 in a relatively non-rotatable manner, and ameshing member 2C is connected to the second rotational member 14 so asto be axially movable but relatively non-rotatable relative to thesecond rotational member 14. The electromagnetic clutch device 1Bconnects, in a torque transmittable manner, the second rotational member14 to a first rotational member 15 provided coaxially with the secondrotational member 14 and supported by a housing 10 in a relativelyrotatable manner.

Further, in the third to fifth embodiments, the second rotational member12, 13 makes direct contact with the first rotational member 11B.However, in the present embodiment, a ring-shaped friction member 8 isplaced between the meshing member 2C and the first rotational member 15,and the friction member 8 receives a pressing force toward the firstrotational member 15 via a plurality of keys 9 elastically engaged withthe meshing member 2C within a predetermined range, thereby causing afriction torque between the friction member 8 and the first rotationalmember 15. The meshing member 2C is axially biased by a plurality ofcoil springs 200 placed between the meshing member 2C and a flangeportion 143 of the second rotational member 14 (described later), andthe plurality of keys 9 is elastically pressed against the meshingmember 2C by a key spring 900. The following describes a configurationof each of these members in detail.

The first rotational member 15 is rotatably supported by a ball bearing16 placed between the first rotational member 15 and a first housingmember 101. The first rotational member 15 integrally includes: a shaftportion 151 supported by the ball bearing 16; a flange portion 152formed so as to project radially outwardly from asecond-rotational-member-14-side end of the shaft portion 151; a splineportion 153 serving as a first meshing portion formed in an outerperiphery of the flange portion 152; and a cylindrical portion 154extending from an axial end of the flange portion 152 on asecond-rotational-member-14 side (an opposite side to the shaft portion151) further toward the second rotational member 14.

An outside diameter of the cylindrical portion 154 is formed so as to besmaller than an outside diameter of the flange portion 152, and an outerperipheral surface 154 a thereof frictionally slides over the frictionmember 8, thereby causing a friction torque that synchronizes a rotationof the first rotational member 15 with a rotation of the secondrotational member 14. That is, in the present embodiment, the outerperipheral surface 154 a of the cylindrical portion 154 of the firstrotational member 15 corresponds to the first friction surface of thepresent invention.

The meshing member 2C integrally includes: a cylindrical portion 25provided with a spline portion 251 formed on an inner peripheral surfaceof the cylindrical portion 25 so as to serve as a second meshing portionmeshed with the spline portion 153 of the first rotational member 15;and an annular pressed portion 26 formed in one axial end of thecylindrical portion 25 so as to project inwardly. A rolling bearing 6abuts with one end surface of the pressed portion 26 in an axialdirection of the meshing member 2C, and a plurality of coil springs 200abuts with the other end surface thereof. The coil springs 200 bias themeshing member 2C toward the cam member 5, and in response to an axialmovement of the armature 4, the cam member 5 axially moves the meshingmember 2C toward the first rotational member 15 against a biasing forceof the coil springs 200.

FIG. 21 illustrates the second rotational member 14. FIG. 21A is a viewillustrating an axial end surface of the second rotational member 14viewed from a first-rotational-member-15 side along the rotation axis O,FIG. 21B is a sectional view taken along a line A-A in FIG. 21A, andFIG. 21C is a view illustrating an axial end surface of the secondrotational member 14 viewed from an opposite side to thefirst-rotational-member-15 side (a side closer to an opening 102 a of asecond housing member 102) along the rotation axis O.

The second rotational member 14 has a bottomed cylindrical shape inwhich a shaft accommodation hole 14 a in which to accommodate one end ofa shaft 100 is formed in a center. An inner peripheral spline portion 14b splined to an outer peripheral spline portion 100 a of the shaft 100is formed on an inner surface of the shaft accommodation hole 14 a. Thesecond rotational member 14 and the shaft 100 are connected in arelatively non-rotatable manner due to splining between the innerperipheral spline portion 14 b and the outer peripheral spline portion100 a, and an axial relative movement thereof is regulated by a snapring 100 c.

The second rotational member 14 integrally includes: a cylindricalportion 140 in which the shaft accommodation hole 14 a is formed; abottom portion 141 having an axial bottom face 14 c of the shaftaccommodation hole 14 a; a boss portion 142 axially projecting from thatsurface of the bottom portion 141 which is opposite to the bottom face14 c; a flange portion 143 formed so as to project radially outwardlyfrom an outer peripheral surface 140 a of the cylindrical portion 140;and a spline portion 144 formed in an outer periphery of the flangeportion 143.

The cylindrical portion 140 includes: a large diameter portion 140 a towhich the cam member 5 is outwardly engaged; and a small diameterportion 140 b formed in that end of the cylindrical portion 140 which isopposite to the bottom portion 141, so as to be supported by a ballbearing 18. The flange portion 143 is formed so as to project radiallyoutwardly from the large diameter portion 140 a, and the cam member 5 isoutwardly engaged with that part of the large diameter portion 140 awhich is closer to the small diameter portion 140 b than the flangeportion 143. The cam member 5 is loosely fitted to the large diameterportion 140 a of the cylindrical portion 140, and is axially movable andrelatively rotatable relative to the second rotational member 14.

The flange portion 143 has a plurality of spring accommodation holes 143a in each of which to accommodate one end of each of the plurality ofcoil springs 200, and the plurality of spring accommodation holes 143 ais formed so as to be opened toward the small diameter portion 140 b.Further, the flange portion 143 has an annular key-spring accommodationportion 143 b in which to accommodate the key spring 900, and thekey-spring accommodation portion 143 b is formed so as to be openedtoward the boss portion 142. Furthermore, the flange portion 143includes a plurality of key accommodation grooves 143 c formed so as tobe hollowed radially inwardly from an outer peripheral surface of theflange portion 143. Each of the key accommodation grooves 143 caccommodates therein an end of a key 9.

The key-spring accommodation portion 143 b is formed in a wholecircumference of the flange portion 143 along a circumferentialdirection of the second rotational member 14. The key accommodationgroove 143 c communicates with the key-spring accommodation portion 143b so that the key 9 of which one end is accommodated in the keyaccommodation groove 143 c receives, from the key spring 900, a biasingforce toward a radially outward direction of the second rotationalmember 14.

In the present embodiment, three key accommodation grooves 143 c areformed in the flange portion 143 at regular intervals every in acircumferential direction, and nine spring accommodation holes 143 a areformed between the three key accommodation grooves 143 c. That is, threespring accommodation holes 143 a are formed between a pair of keyaccommodation grooves 143 c adjacent to each other in thecircumferential direction.

Further, in the present embodiment, a plurality of (two) key springs 900is accommodated in the key-spring accommodation portion 143 b. Each ofthe key springs 900 is an elastic member made from a C-shaped springsteel, for example, and is accommodated in the key-spring accommodationportion 143 b in a state where the each of the key springs 900 iselastically deformed by the plurality of keys 9 so as to be reduced indiameter.

The spline portion 251 of the meshing member 2C is splined to the splineportion 144 of the second rotational member 14. Due to the splining, themeshing member 2C is connected to the second rotational member 14 so asto be axially movable but relatively non-rotatable relative to thesecond rotational member 14.

FIG. 22 illustrates the friction member 8. FIG. 22A is a view of anaxial end surface of the friction member 8 viewed from aflange-portion-143 side of the second rotational member 14 along therotation axis O, FIG. 22B is a sectional view taken along a line B-B inFIG. 22A, and FIG. 22C is an enlarged perspective view of part of anouter periphery of the friction member 8 viewed from the flange-portion143 side.

The friction member 8 has a ring shape outwardly engaged with thecylindrical portion 154 of the first rotational member 15, and its innerperipheral surface 8 a is opposed to the outer peripheral surface 154 aof the cylindrical portion 154 of the first rotational member 15. Theouter peripheral surface 154 a is a tapered surface formed to beinclined with respect to an axial direction parallel to the rotationaxis O so that its outside diameter is reduced toward an axial tip sideof the cylindrical portion 154. The inner peripheral surface 8 a of thefriction member 8 is a tapered surface formed to be parallel to theouter peripheral surface 154 a of the cylindrical portion 154.

The friction member 8 is axially movable relative to the firstrotational member 15, and when the inner peripheral surface 8 a isaxially pressed against the outer peripheral surface 154 a of thecylindrical portion 154, a friction torque is caused between thefriction member 8 and the first rotational member 15. That is, in thepresent embodiment, the inner peripheral surface 8 a of the frictionmember 8 corresponds to the second friction surface of the presentinvention.

Further, a key accommodation groove 8 b in which to accommodate an endof the key 9 is formed in the friction member 8. In the presentembodiment, three key accommodation grooves 8 b are formed at regularintervals in a circumferential direction so as to correspond to threekey accommodation grooves 143 c formed in the flange portion 143 of thesecond rotational member 14. Further, a spline portion 81 provided witha plurality of spline teeth 811 is formed in an outer periphery of thefriction member 8. Each of the spline teeth 811 has a pair of chamfersurfaces 811 a inclined symmetrically from a central part of a toothflank on a key-accommodation-groove-8 b side in an axial directionparallel to the rotation axis O with the central part being taken as avertex.

FIG. 23 illustrates the key 9. FIG. 23A is a side view of the key 9,FIG. 23B is a view of an axial end surface of the key 9 viewed from acam-member-5 side, and FIG. 23C is a perspective view of the key 9.

The key 9 integrally includes: a base portion 90 having a rectangularsolid shape; and a projection portion 91 formed so as to project towardthe cylindrical portion 21 of the meshing member 2C from an outersurface 90 a of the base portion 90 opposed to the cylindrical portion21 of the meshing member 2C. The projection portion 91 is formed as aflat plane of which a tip end surface 91 a in a projection direction ofthe projection portion 91 is parallel to the outer surface 90 a of thebase portion 90. Further, in both ends of the projection portion 91 inthat longitudinal direction of the key 9 which is parallel to therotation axis O, the tip end surface 91 a of the projection portion 91is connected to the outer surface 90 a of the base portion 90 viainclined surfaces 91 b, 91 c. An angle formed between the outer surface90 a of the base portion 90 and each of the inclined surfaces 91 b, 91 cis an obtuse angle, and the projection portion 91 is formed in a bellshape in a side view illustrated in FIG. 23A.

The key 9 is placed so that one end surface 90 d in a longitudinaldirection of the base portion 90 is opposed to an axial bottom face 8 cof the key accommodation groove 8 b of the friction member 8, and theother end surface 90 e in the longitudinal direction of the base portion90 is opposed to the pressed portion 26 of the meshing member 2C. Theinclined surface 91 b of the projection portion 91 is formed closer tothe one end surface 90 d than the tip end surface 91 a, and the inclinedsurface 91 c is formed closer to the other end surface 90 e than the tipend surface 91 a.

Further, a hollow portion 90 c formed to be hollowed toward the outersurface 90 a is formed on an inner surface 90 b on a backside of thebase portion 90 of the key 9, relative to the outer surface 90 a. Asillustrated in FIG. 20, the plurality of key springs 900 is fitted inthe hollow portion 90 c.

As illustrated in FIG. 20, a recessed portion 250 to which theprojection portion 91 of the key 9 is elastically engaged is formed inthe spline portion 251 of the meshing member 2C. The recessed portion250 is formed such that a radial height of a plurality of spline headparts 251 b constituting the spline portion 251 of the meshing member 2Cis partially lowered in an axial direction.

The plurality of keys 9 is elastically engaged with the meshing member2C within a predetermined range where the spline portion 251 is notmeshed with the spline portion 153 of the first rotational member 15,out of an range of an axial movement of the meshing member 2C. Morespecifically, the projection portions 91 of the keys 9 elastically lockthe recessed portion 250 of the meshing member 2C in a state where alocking portion 19 locks a first locked portion 51 of the cam member 5.In a state where the locking portion 19 locks a third locked portion 53or a fourth locked portion 54 of the cam member 5, the plurality of keys9 moves inwardly in a radial direction of the second rotational member14 due to an axial movement of the meshing member 2C, so that theprojection portions 91 thereof are separated from the recessed portion250 of the meshing member 2C. That is, due to the axial movement of themeshing member 2C from a predetermined range where the spline portion251 of the meshing member 2C is not meshed with the spline portion 153of the first rotational member 15 to a position where the splineportions 251, 153 are meshed with each other, the projection portions 91of the keys 9 are separated from the recessed portion 250 of the meshingmember 2C.

When a first state (see FIG. 16A) where the locking portion 19 locks thefirst locked portion 51 of the cam member 5 is shifted to a second statewhere the armature 4 presses the cam member 5 toward the meshing member2C, the inner peripheral surface 8 a of the friction member 8 is axiallypressed against the outer peripheral surface 154 a of the cylindricalportion 154 of the first rotational member 15, thereby causing afriction torque that synchronizes a rotation of the first rotationalmember 15 with a rotation of the second rotational member 14. That is,even in a case where there is a rotation speed difference between arotation speed of the first rotational member 15 and a rotation speed ofthe second rotational member 14, the rotational speed difference isreduced by the friction torque, thereby resulting in that the splineportion 251 of the meshing member 2 c is smoothly splined to the splineportion 153 of the first rotational member 15.

FIGS. 24A to 24C are operation explanatory views to describe anoperation of the electromagnetic clutch device 1B.

FIG. 24A illustrates an uncoupled state in which the meshing member 2Cis placed within the predetermined range where the spline portion 251 isnot meshed with the spline portion 153 of the first rotational member15, in the range of the axial movement of the meshing member 2C, and thefirst rotational member 15 and the second rotational member 14 arerotatable relative to each other. In the uncoupled state, the projectionportion 91 of the key 9 is fitted to the recessed portion 250 of themeshing member 2C. The recessed portion 250 of the meshing member 2C hasa bottom face 250 a opposed to the tip end surface 91 a of theprojection portion 91, an inclined surface 250 b opposed to one inclinedsurface 91 b of the projection portion 91, and an inclined surface 250 copposed to the other inclined surface 91 c of the projection portion 91.

FIG. 24B illustrates a state where the armature 4 presses the cam member5 toward the meshing member 2C in the uncoupled state, and due tofitting between the projection portion 91 of the key 9 and the recessedportion 250 of the meshing member 2C, one end surface 90 d of the baseportion 90 of the key 9 in the longitudinal direction is pressed againstthe bottom face 8 c of the key accommodation groove 8 b of the frictionmember 8.

The friction member 8 receives an axial pressing force of the armature 4via the plurality of keys 9, so that the inner peripheral surface 8 a ispressed against the outer peripheral surface 154 a of the cylindricalportion 154 of the first rotational member 15 so as to cause a frictiontorque. When the meshing member 2C further axially moves, the axialpressing force of the armature 4 is received by the chamfer surfaces 811a, thereby increasing the friction torque. After that, the splineportion 251 of the meshing member 2C is splined to the spline portion 81of the friction member 8. The key accommodation groove 8 b of thefriction member 8 is configured such that a width w1 of the keyaccommodation groove 8 b in a circumferential direction of the frictionmember 8 is wider than a width w2 of the base portion 90 of the key 9 inthe circumferential direction so that the spline portion 251 of themeshing member 2C is splined to the spline portion 81 in a state whereone end of the key 9 is accommodated in the key accommodation groove 8b. A difference between the width w1 (see FIG. 22A) of the keyaccommodation groove 8 b and the width w2 (see FIG. 23B) of the baseportion 90 of the key 9 corresponds to a half phase of a spline pitch ofthe spline portion 81.

FIG. 24C is a coupled state of the first rotational member 15 and thesecond rotational member 14 in which coupled state the meshing member 2Cfurther axially moves toward the first rotational member 15, and thespline portion 251 is meshed with the spline portion 153 of the firstrotational member 15.

In a course of shifting from the state illustrated in FIG. 24B to thestate illustrated in FIG. 24C, the key 9 moves radially inwardly so asto be distanced from the cylindrical portion 25 of the meshing member 2Cinside the key accommodation groove 8 b of the friction member 8 and thekey accommodation groove 143 c of the second rotational member 14, sothat the projection portion 91 of the key 9 is separated from therecessed portion 250 of the meshing member 2C. That is, the key 9 movesradially inwardly against a biasing force of the key springs 900, due toabutment of the inclined surface 91 c of the projection portion 91 withthe inclined surface 250 c of the recessed portion 250 of the meshingmember 2C.

Further, when the armature 4 further reciprocates between a firstposition and a second position from the coupled state illustrated inFIG. 24C and the locking portion 19 locks the first locked portion 51 ofthe cam member 5, the meshing member 2C axially moves toward the lockingportion 19 due to a biasing force of the coil springs 200. Hereby, themeshing between the spline portion 251 of the meshing member 2C and thespline portion 153 of the first rotational member 15 is released,thereby causing the first rotational member 15 and the second rotationalmember 14 to be in the uncoupled state.

According to the sixth embodiment described above, since the innerperipheral surface 8 a of the friction member 8 is axially pressedagainst the outer peripheral surface 154 a of the cylindrical portion154 of the first rotational member 15 via the plurality of keys 9 so asto cause a friction torque, it is possible to mesh the spline portion251 of the meshing member 2C with the spline portion 153 of the firstrotational member 15 after a rotation of the first rotational member 15is synchronized with a rotation of the second rotational member 14.Accordingly, even in a case where the first rotational member 15 and thesecond rotational member 14 rotate relative to each other with arotational speed difference, it is possible to smoothly shift from theuncoupled state to the coupled state.

Further, after a friction torque is caused between the friction member 8and the first rotational member 15, the plurality of keys 9 is separatedfrom the recessed portion 250 of the meshing member 2C due to a furthermovement of the meshing member 2C toward the first rotational member 15.Accordingly, it is possible to mesh the spline portion 251 of themeshing member 2C with the spline portion 153 of the first rotationalmember 15 without disturbing the axial movement of the meshing member2C.

The electromagnetic clutch device 1 of the present invention has beendescribed above based on the third to sixth embodiments. However, thepresent invention is not limited to these embodiments, and isperformable in various modifications within a range which does notdeviate from the gist of the present invention. For example, it is alsopossible to use the electromagnetic clutch device 1 for purposes exceptfor a purpose of transmitting a driving force of a vehicle.

What is claimed is:
 1. An electromagnetic clutch device configured toconnect a first rotational member to a second rotational member in atorque transmittable manner, the electromagnetic clutch devicecomprising: a meshing member including a second meshing portion to bemeshed with a first meshing portion formed in the first rotationalmember, the meshing member being connected to the second rotationalmember in an axially movable but relatively non-rotatable manner; anelectromagnetic coil that causes a magnetic force by currentapplication; an armature that axially moves due to the magnetic force; acylindrical cam member that is rotatable relative to the armature andthat axially moves the meshing member so that the second meshing portionis meshed with the first meshing portion; and a locking portion providedso as to be axially immovable relative to the first rotational memberand to be non-rotatable relative to the armature, wherein: the cammember is provided with a plurality of locked portions to be locked bythe locking portion at different axial positions of the cam member, suchthat the plurality of locked portions is formed adjacent to each otherin a circumferential direction; the cam member rotates only by a firstpredetermined angle due to an axial movement of the armature from afirst position to a second position, and the cam member further rotatesonly by a second predetermined angle due to a movement of the armaturefrom the second position to the first position; and when locking of thelocking portion is shifted from one of the plurality of locked portionsto another locked portion circumferentially adjacent thereto so that thelocking portion locks the another locked portion at a different axialposition, the second meshing portion is meshed with the first meshingportion.
 2. The electromagnetic clutch device according to claim 1,further comprising: a biasing member that biases the armature from thesecond position to the first position.
 3. The electromagnetic clutchdevice according to claim 1, wherein: the armature is axially movablebut non-rotatable relative to the electromagnetic coil.
 4. Theelectromagnetic clutch device according to claim 1, wherein: theplurality of locked portions is formed in at least three differentpositions in an axial direction of the cam member; and when the armaturerepeats a movement from the first position to the second positionseveral times, the second meshing portion of the meshing member ismeshed with the first meshing member of the first rotational member. 5.The electromagnetic clutch device according to claim 1, furthercomprising: a biasing member that biases the meshing member in adirection where the second meshing portion is meshed with the firstmeshing portion; and a pressing mechanism including the locking portionthat presses the meshing member against a biasing force of the biasingmember due to an axial movement of the armature so as to axially movethe meshing member, the locking portion being provided so as to berelatively non-rotatable relative to a housing that support theelectromagnetic coil, wherein the cam member is cylindrical, thepressing mechanism being configured such that, in response to an axialmovement of the armature, locking of the locking portion is shifted fromone of the plurality of locked portions to another locked portion placedat a different axial position, wherein: when the cam member moves to anopposite side to the meshing member in response to the axial movement ofthe armature, the second meshing portion is meshed with the firstmeshing portion due to the biasing force of the biasing member.
 6. Theelectromagnetic clutch device according to claim 5, wherein: theplurality of locked portions is formed in at least three differentpositions in an axial direction of the cam member; and the meshingmember is configured such that, when a state where the locking portionlocks a locked portion formed in a position farthest from the meshingmember among the plurality of locked portions is released so that thelocking portion locks a locked portion formed in a position nearest tothe meshing member, the second meshing portion is meshed with the firstmeshing portion due to the biasing force of the biasing member.
 7. Theelectromagnetic clutch device according to claim 5, wherein: in the cammember, the plurality of locked portions is formed adjacent to eachother in a circumferential direction; when the armature axially movesfrom a first position to a second position, the armature presses the cammember toward the meshing member so as to rotate the cam member only bya first predetermined angle; and when the armature moves from the secondposition to the first position, the cam member further rotates by asecond predetermined angle, so that locking of the locking portion isshifted from one of the plurality of locked portions to another lockedportion adjacent thereto in the circumferential direction.
 8. Theelectromagnetic clutch device according to claim 7, wherein: when thearmature is placed in the first position, the locking portion abuts withan axial end surface and a circumferential side surface of the lockedportion, and the pressing projection of the armature is opposed to theaxial end surface in a position distanced from the side surface in thecircumferential direction of the cam member; and when the armature movesto the second position, the cam member rotates by the firstpredetermined angle, so that the pressing projection abuts with the sidesurface and the locking portion is opposed to an axial end surface ofthe another locked portion.
 9. The electromagnetic clutch deviceaccording to claim 5, wherein: the second meshing portion of the meshingmember is always meshed with the first meshing member; and when themeshing member axially moves, the second meshing portion is also meshedwith the second rotational member, so that the first rotational memberis connected to the second rotational member in a torque transmittablemanner.
 10. The electromagnetic clutch device according to claim 5,wherein: the pressing mechanism includes a locking portion provided soas to be axially immovable relative to the second rotational member andto be non-rotatable relative to the armature; and in a course ofshifting from an uncoupled state to a coupled state along with an axialmovement of the cam member due to an axial movement of the armature, afriction torque is caused so as to synchronize a rotation of the firstrotational member with a rotation of the second rotational member. 11.The electromagnetic clutch device according to claim 10, wherein: thefriction torque is caused when a second friction surface on afirst-rotational-member side is axially pressed against a first frictionsurface on a second-rotational-member side due to the axial movement ofthe cam member.
 12. The electromagnetic clutch device according to claim11, wherein: the armature performs a pressing operation to press the cammember toward the meshing member before the locking portion locks theanother locked portion; and the second friction surface is pressedagainst the first friction surface due to the pressing operation. 13.The electromagnetic clutch device according to claim 12, wherein: thesecond friction surface is formed in a friction member axially movablerelative to the second rotational member; and the friction memberreceives a pressing force toward the second rotational member via anengage and disengage member to be elastically engaged with the meshingmember within a predetermined range where the second meshing portion isnot meshed with the first meshing portion in an axially movable range ofthe meshing member.
 14. The electromagnetic clutch device according toclaim 13, wherein: the engage and disengage member and the meshingmember are configured such that a projection portion formed in eitherone of the engage and disengage member and the meshing member iselastically engaged with a recessed portion formed in the other onethereof; and the projection portion is separated from the recessedportion due to an axial movement of the meshing member from thepredetermined range to a position in which the second meshing portion ismeshed with the first meshing portion.
 15. The electromagnetic clutchdevice according to claim 12, wherein: the second friction surface isformed in the meshing member.
 16. The electromagnetic clutch deviceaccording to claim 15, wherein: the first friction surface and thesecond friction surface are tapered surfaces inclined in the axialdirection.
 17. The electromagnetic clutch device according to claim 12,wherein: the first rotational member includes a cylindrical fixingmember, and a moving member projecting radially outwardly and providedso as to be axially movable but relatively non-rotatable relative to thefixing member; and the moving member is placed between the secondrotational member and the meshing member.
 18. The electromagnetic clutchdevice according to claim 5, wherein: the plurality of locked portionsis formed in at least three different positions in the axial directionof the cam member.
 19. An electromagnetic clutch device configured toconnect a first rotational member to a second rotational member in atorque transmittable manner, the electromagnetic clutch devicecomprising: a meshing member including a second meshing portion to bemeshed with a first meshing portion formed in the first rotationalmember, the meshing member being connected to the second rotationalmember in an axially movable but relatively non-rotatable manner; anelectromagnetic coil that causes a magnetic force by currentapplication; an armature that axially moves due to the magnetic force; acylindrical cam member that axially moves the meshing member so that thesecond meshing portion is meshed with the first meshing portion; and alocking portion provided so as to be axially immovable relative to thefirst rotational member and to be non-rotatable relative to thearmature, wherein: the cam member is provided with a plurality of lockedportions to be locked by the locking portion at different axialpositions of the cam member, such that the plurality of locked portionsis formed adjacent to each other in a circumferential direction; the cammember rotates only by a first predetermined angle due to an axialmovement of the armature from a first position to a second position, andthe cam member further rotates only by a second predetermined angle dueto a movement of the armature from the second position to the firstposition; and when locking of the locking portion is shifted from one ofthe plurality of locked portions to another locked portioncircumferentially adjacent thereto so that the locking portion locks theanother locked portion at a different axial position, the second meshingportion is meshed with the first meshing portion, wherein: the pluralityof locked portions includes a first locked portion and a second lockedportion, each locked by the locking portion at a different axialposition; the first locked portion and the second locked portion areformed alternately in the circumferential direction, and when thearmature reciprocates between the first position and the second positionseveral times, a state where the locking portion locks the first lockedportion and a state where the locking portion locks the second lockedportion are switched; and when the locking portion locks the secondlocked portion, the first meshing portion is meshed with the secondmeshing portion, and when the locking portion locks the first lockedportion, the meshing between the first meshing portion and the secondmeshing portion is released.
 20. An electromagnetic clutch deviceconfigured to connect a first rotational member to a second rotationalmember in a torque transmittable manner, the electromagnetic clutchdevice comprising: a meshing member including a second meshing portionto be meshed with a first meshing portion formed in the first rotationalmember, the meshing member being connected to the second rotationalmember in an axially movable but relatively non-rotatable manner; anelectromagnetic coil that causes a magnetic force by currentapplication; an armature that axially moves due to the magnetic force; acylindrical cam member that axially moves the meshing member so that thesecond meshing portion is meshed with the first meshing portion; and alocking portion provided so as to be axially immovable relative to thefirst rotational member and to be non-rotatable relative to thearmature, wherein: the cam member is provided with a plurality of lockedportions to be locked by the locking portion at different axialpositions of the cam member, such that the plurality of locked portionsis formed adjacent to each other in a circumferential direction; the cammember rotates only by a first predetermined angle due to an axialmovement of the armature from a first position to a second position, andthe cam member further rotates only by a second predetermined angle dueto a movement of the armature from the second position to the firstposition; and when locking of the locking portion is shifted from one ofthe plurality of locked portions to another locked portioncircumferentially adjacent thereto so that the locking portion locks theanother locked portion at a different axial position, the second meshingportion is meshed with the first meshing portion, wherein: the cammember is configured such that an axial end surface of each of theplurality of locked portions is formed so as to be inclined in thecircumferential direction, and the cam member receives an axial biasingforce at which the axial end surface is pressed against the lockingportion; the armature includes a pressing projection that presses thecam member toward the meshing member by abutting with the axial endsurface of the cam member; and the cam member rotates by the firstpredetermined angle due to sliding between the axial end surface and thepressing projection.
 21. The electromagnetic clutch device according toclaim 20, wherein: when the axial end surface of the cam member thatreceives the biasing force slides over the locking portion, the cammember rotates relative to the locking portion by the secondpredetermined angle.
 22. The electromagnetic clutch device according toclaim 21, wherein: when the armature is placed in the first position,the locking portion abuts with a wall surface of the locked portion in acircumferential direction of the cam member and the axial end surfacethereof; and when the armature moves to the second position, the cammember rotates by the first predetermined angle so that the pressingprojection abuts with the wall surface and the locking portion isopposed to the axial end surface of the another locked portion.
 23. Theelectromagnetic clutch device according to claim 20, further comprising:a rolling bearing placed between the meshing member and the cam member;and an elastic member that elastically presses the meshing member towardthe cam member, wherein: the cam member receives a pressing force of theelastic member as the biasing force from the meshing member via therolling member.